Development of a 3D-printed bra with an incorporated prosthesis for post-mastectomy women

Abstract

Background:

Women who have undergone mastectomy and do not undergo reconstruction often face challenges with existing bras and prostheses. Mismatches between generic prostheses and individual mastectomy cases result in physical and mental discomfort, such as pain, sweating, asymmetry, and concerns about prosthesis movement. Existing solutions are limited in their ability to address these challenges effectively.

Objectives:

This study aims to develop a workflow for designing and fabricating a lightweight post-mastectomy bra with an incorporated prosthesis to improve fit, symmetry, and comfort.

Design:

We developed a customization and fabrication workflow based on a three-dimensional (3D) scan and the manipulation of its geometry to achieve fit and symmetry. We leverage the 3D-printed spacer fabric technique to produce a lightweight, breathable structure.

Methods:

We conducted mechanical tests to determine printing parameters and evaluate the compression properties of the prosthesis and the bra materials. Additionally, we conducted a wear test for 10 women who underwent a mastectomy. A personalized bra was printed for each, and their feedback on fit and comfort was collected weekly over a 3-week test period.

Results:

The printed bras were lightweight (150–250 g), breathable, and provided improved symmetry. The mechanical tests confirmed comparable softness to silicone prostheses at significantly lower weight. The user study results show that the custom bras offer several advantages, including reduced weight and improved symmetry, though some participants noted mild fit and texture issues.

Conclusion:

Integrating the prosthesis into a 3D-printed bra offers a promising personalized solution for post-mastectomy women. This approach enhances comfort, symmetry, and emotional well-being, however, further improvements need to be made to improve the material and tactility.

Plain language summary

Many women who undergo a mastectomy are unable to have breast reconstruction for various reasons. These women usually choose to wear a silicone prosthesis placed in a special bra. This solution often exacerbates physical and mental discomfort due to a mismatch between the bra and the body. Women often suffer from excessive sweating, rashes, pressure, and shoulder pain from the prosthesis’s weight. In addition, there are issues of asymmetry, and they often fear that the prosthesis might move or fall, making them feel uncomfortable and embarrassed. The paper addresses these challenges by introducing a novel approach in which a prosthesis is incorporated into a 3D-printed, custom-fitted bra. Each bra is meticulously customized to the unique anatomy of the post-mastectomy woman, utilizing 3D scanning technology to precisely capture body contours. This data is then processed and refined to generate a digital blueprint, enabling the production of a bespoke bra tailored to the individual’s needs. Leveraging advanced 3D Printed Spacer Fabrics (3DSF) technology enables the creation of a breathable, lightweight bra that is up to 30% lighter than a silicone prosthesis. We use two scans, one with a bra and one without, to design the prosthetic shape in order to achieve a symmetrical appearance. This study was an evaluation by a user study that included 10 women who wore the bra for a few hours a day over a period of three weeks. The participants provided feedback on the fit, comfort, and self-perception of femininity. The results show that most women are happy with the weight reduction and report a decrease in sweating, while feedback on fit and overall satisfaction varies. We hope that this research will raise awareness and encourage further exploration to improve the lives of mastectomy survivors.

Introduction

Over 2 million women are diagnosed with breast cancer each year. ¹ Thirty-six percent of the women diagnosed with breast cancer undergo a mastectomy, ² from which 80% wear prostheses. ³ Sometimes, the diagnosed women undergo immediate breast reconstruction or wait to finish radiotherapy treatments and radiation changes. Many women choose not to undergo reconstruction because they fear the complexity of the operation and want to avoid future complications. ⁴ Therefore, many women are left with one breast or no breasts at all. ⁵

The solutions available for women who have had a mastectomy are special bras and silicone prostheses that fit inside a bra. ⁶ As every woman is unique in body and shape size, many difficulties accompany the fit of generic size prostheses and the bra for each woman.^7,8 These women also face various problems; physically, they often suffer from excessive sweating and rashes as a result of wearing the prosthesis, in addition to suffering from pressure and pain on the shoulders as a result of its weight. ⁹ In addition, they also fear that the prosthesis will move, fall, or not sit properly in the bra. Apart from comfort-related aspects, there are mental difficulties faced by women who have had a mastectomy. ¹⁰ In addition to the physical and mental distress, purchasing prostheses and mastectomy bras also involves economic and cultural factors. ¹¹

The numerous issues inherent in prostheses and mastectomy bras have underscored the critical necessity for a comprehensive solution. Such a solution should include a prosthesis that is lightweight to alleviate shoulder pressure and well-ventilated to counteract excessive perspiration. ¹² It is crucial for the prosthesis to establish symmetry with the existing breast and to address prosthesis displacement within the bra. To effectively tackle these challenges, a personalized bra customization process must be developed, tailoring solutions to each individual’s specific concerns. Such a solution will optimize bra comfort and empower women to feel at ease with their altered physique.

Among the various technologies explored, three-dimensional (3D) printing emerged as the most suitable for personalization, utilizing 3D scans of each woman to create bras that align precisely with their body contours and scars. ¹³ Custom 3D-printed prostheses have become commonplace in the realm of limb prosthetics, with numerous researchers and designers focusing on providing affordability and customization. ¹⁴ While innovative solutions for mastectomy have been relatively scarce, there has been a noticeable increase in research and projects in recent years. Companies now offer customized 3D-printed silicone prostheses based on individual scans, exemplified by projects such as MyReflection and ONEbra.^15,16 However, these solutions do not solve issues of displacement and ventilation of the prosthesis.

To address the common problem of prosthesis displacement inside bras, a unique and innovative approach is employed in this study, in which the prosthesis is printed as an integral part of the bra. Three-dimensional scans capture precise shapes and contours, considering any post-mastectomy alterations or scars. Using 3D scan data, both the bra and the prosthesis are tailored to fit the woman’s unique chest shape perfectly. Instead of producing a separate prosthesis placed inside the bra, the prosthesis is printed directly as an inseparable part of the bra. This ensures a seamless fit and eliminates issues related to prosthesis movement within the bra.

To explore the customization of mastectomy bras, 3D scans were conducted on 10 women who underwent a mastectomy, addressing individual needs and ensuring a precise fit. The bras, including the prostheses, were 3D printed as a single unit, and tensile tests were performed to assess material durability and flexibility. To compare the properties of the 3D-printed prosthesis with a silicone prosthesis, compression tests were conducted. During the process, a systematic approach of 3D scanning, prosthesis personalization, and 3D printing was developed.

Materials and methods

Our approach for fitting the bra is to 3D print the entire bra in one single piece. The geometry of the bra should perfectly match the body and mastectomy scars of the woman and provide symmetry with the healthy breast on the outside. To create this geometry, we scan the woman’s body using an ARTEC-EVA handheld 3D scanner (Senningerberg, Luxembourg). Each woman was scanned twice—once with her preferred prosthesis and bra, and second without a bra. The scan geometries from these two scans were processed and stitched together to generate the inner and outer geometries of the 3D-printed bra, as described in section “Developing a customization workflow for the bras.”

Three-dimensional printing the bra geometry using the standard 3D printing workflow would have generated a stiff, heavy, and unventilated material. Therefore, an alternative printing workflow is required. The printing method found to be the most suitable for the bra is 3D-printed spacer fabric (3DSF). ¹⁷ 3DSF is a printing technique for fused depositing modeling 3D printers, which utilizes Bridging—the ability to print material strands in mid-air. In this method, the printer stretches fibers between two surface faces, thereby crafting a structure with a similar construction to knitted spacer fabrics. Indeed, 3DSF structures are endowed with attributes such as softness, lightness, and breathability. The printed material is thermoplastic polyurethane (TPU), a flexible material suitable for 3D printing. ¹⁸ The 3DSF can be sewn and attached to strips and fabrics similarly to knitted spacer fabrics. It is possible to wash this material in a washing machine. ¹⁹

The 3DSF technique enables precise parameter adjustments for enhanced printing efficiency, mechanical properties, and product quality. These parameters were examined in the context of suitability as the material for a bra. Samples were 3D printed and analyzed using tensile tests. A 3DSF breast prosthesis was evaluated for its compression properties and compared with a silicone prosthesis. Finally, a 3D-printed bra was developed based on these parameters.

For all the models and samples, we utilize a FlashForge Creator 4 3D printer and a designated printing head for 2.85 mm flexible filaments. The nozzle size is 0.4 mm, and it is calibrated to 230°C. The printing bed size is 445 × 400 mm, set to 40°C.

Tensile tests

To identify the optimal printing parameters for achieving textile-like properties, various samples with different parameters were printed. Tensile tests were conducted on these samples to assess their flexibility and structural integrity. The tests were performed in vertical and horizontal directions using an Instron 3345 machine (Norwood, MA, USA). Each sample was stretched at a rate of 7 mm/min, measuring the material’s elongation ability and load capacity until it tore. The samples were printed from two materials. Polymaker PolyFlex TPU90—flexible material for 3D printing, and NinjaTek Chinchilla TPE75—a very flexible material for 3D printing, intended for wearable accessories.

For this test, 10 samples were 3D printed from each material: 5 were tested in the horizontal direction and 5 in the vertical direction (Figure 1(a)). For each material, all printing parameters were identical except for the amount of extrusion, which is controlled by a factor that we refer to as the eFactor. The eFactor is used to determine the amount of material being extruded for each printing stand, which affects the weight and durability of the material (Table 1). Samples were printed with eFactor values of 50, 65, 80, 95, and 110. The printing speed between the materials differed: 2500 mm/min for the PolyFlex and 1000 mm/min for the Chinchilla. The sample size was measured at 25 mm × 55 mm × 3 mm.

Figure 1.

Tensile test Thermoplastic Polyurethane (TPU) and Thermoplastic Elastomer (TPE) samples printed in vertical and horizontal orientations. (a) Samples were tested on an Instron device until tear (b). Strain–stress curves for the TPU vertical and horizontal samples (c). Strain-stress curves for the TPE vertical and horizontal samples (d). A silicone prosthesis and a 3D spacer prosthesis, which were used for the compression test (e). Strain–stress curves of three compression test cycles of the silicone and 3D printed prostheses (f).

3D: three-dimensional.

Table 1.

The weight and eFactor parameter for tensile test samples.

eFactor	PolyFlex TPU90 weight (g)	Chinchilla TPE75 weight (g)
50	1.8	1.5
65	1.4	1.2
80	1.2	1.1
95	1	0.8
110	0.9	0.8

TPU: thermoplastic polyurethane; TPE: Thermoplastic Elastomer.

Compression test of 3DSF versus a silicone prosthesis

The compression behavior of the printed prosthesis was compared with that of a silicone prosthesis through a compression test. The silicone prosthesis that was used is manufactured by Emoena company. ²⁰ This silicone prosthesis was 3D scanned using an Atrec 3D scanner. Based on the scanned geometry, a 3DSF prosthesis was printed using a Polymaker PolyFlex TPU90 with an eFactor of 80 (Figure 1(e)). An Instron 3345 machine was utilized to conduct the compression test, applying pressure to the models in three cycles to assess any material elasticity changes resulting from compression. Each prosthesis underwent 50% compression from the original thickness, with the machine recording the applied force during compression and release. The test measured force in newtons during compression relative to the compression percentage.

Developing a customization workflow for the bras

The bra fitting process involves 3D scanning, processing the scan, creating a suitable bra file, adjusting the 3DSF code, printing the bra, and final processing.

The 3DSF code for bra printing involves two 3D mesh geometrical files—outer and inner—connected by the printed fiber strands to form a 3D textile. Meshmixer software is used to generate these files based on the 3D scans.

The processing of the outer mesh includes smoothing the mastectomy scars in the cleavage area and the area underneath the breasts. This is done to reduce the overhang angles since the printing itself is done without any support material. The cap with the healthy breast is mirrored to the mastectomy side, and then the two cups are joined and cut around the breast perimeter. The breast shape is merged with the body scan, and finally, an overall smoothing process is applied to the entire bra (Figure 2(a)). To generate the inner mesh, the mastectomy side’s cup is replaced with the mastectomy area that is cut out of the scan without the bra. After joining the scan and the cup, a smoothing process was applied for a seamless and smooth appearance (Figure 2(b)). On average, it takes approximately 2 h to edit and prepare the scanned mesh for printing.

Figure 2.

Geometry manipulation of the bra’s outer mesh (a). Geometry manipulation of the bra’s inner mesh (b). The toolpath generation steps: division into layers of the outer mesh and the inner mesh, division of each layer into points, creating segments, and generating the strands between the inner and outer mesh (c). A bra is used during the 3D printing process, and the prosthesis is built between the inner and the outer faces (d).

3D: three-dimensional.

The two meshes are used as input to the 3DSF algorithm. The algorithm divides the mesh geometries into layers at a height of 0.25 mm and then generates a toolpath that stretches fibers between the inner mesh and the outer mesh. Each layer is divided into points, and slightly slanted lines are drawn at each point, following the mesh shapes. These lines are then cut according to the boundary of each layer. The lines cross each other and overlap on the outer shells, which generates an X shape that acts as a spring for providing flexibility and compression properties to the prosthesis (Figure 2(c)).

The bra is printed as a cylinder to provide stability and reduce vibration during the printing process (Figure 2(d)). After printing is complete, the excess material is cut away. The printing times for a single bra range between 20 and 26 hours. The weight before cutting ranges between 200 and 320 g, depending on the dimensions of the scanned woman. Based on the cost of the filament spool, the material cost of each bra is between $10 and $15.

After printing, the bra is cut out from the cylinder, and the cleavage is cut. The cut shape is different for each woman, depending on the location of the mastectomy scars and the woman’s preferences. Twenty millimeters wide diagonal ribbons are sewn around all edges of the bra, including the straps and hooks (Figure 3). The final processed bras weigh between 150 and 250 g.

Figure 3.

A full 3D printed bra from the front and back.

3D: three-dimensional.

Wear testing

To evaluate the fit, comfort, and overall satisfaction of women with our bra solution, we conducted a user study that included 10 participants who had undergone a mastectomy. These women were recruited after responding to a post published in a post-mastectomy Facebook group, inviting women to participate in this study. After receiving the responses, we selected participants based on the following criteria: at least 1 year after mastectomy, not currently undergoing chemotherapy or radiation therapy, willingness and ability to attend 3D scanning sessions, and completion of the 3-week wear test. All participants have provided written consent to publish their anonymized information, including clinical details and images.

The sample size was determined based on feasibility and qualitative design-testing principles typically used in early-stage prototype evaluation. This number was sufficient to capture a range of body geometries and user experiences while allowing for individualized fitting and feedback. A formal statistical power analysis was not conducted, as the study aimed to assess design feasibility, material performance, and user comfort rather than to test a specific hypothesis.

A bespoke bra was fabricated for each participant, based on their body measurements and 3D scans, which were conducted at the Technion or at the participants’ homes. The information of the user study participants is detailed in Table 2. Some of our participants underwent a double mastectomy; therefore, in their case, the size and type of the prosthesis were decided based on the women’s preference. Each participant received the bra for a period of 3 weeks and was asked to wear the bra for 2–3 h every day, while continuing her daily routine.

Table 2.

Details regarding the user testing participants.

Participant number	Age	Years after mastectomy	Mastectomy side	Bra cup size	Waist size (cm)
1	48	1.5	Double	A	67
2	49	1.5	Left	D	78
3	52	2	Double	B	74
4	42	1.5	Left	C	79
5	40	1.5	Double	D	71
6	65	10	Double	B	73
7	70	35	Left	C	90
8	53	9–10	Right	B	77
9	58	2	Double	D	100
10	62	16	Left	C	77

The comfort, fit, and satisfaction with the 3D-printed bra were evaluated using a custom questionnaire that was developed for this research. Once a week, the women were asked to complete a questionnaire via an online form. The survey included both closed-ended questions rated on a 5-point Likert scale and open-ended questions for qualitative feedback. The questionnaire was not a previously validated instrument but was designed specifically for this exploratory design study to capture user experiences related to physical comfort, weight, ventilation, and body confidence.

The experiment spanned a period of 6 months. This timeline includes the 3D scanning process, the design and fabrication of a bespoke bra, and the collection of user feedback after 3 weeks of use.

This study followed the Template for Intervention Description and Replication (TIDieR) checklist and guide to ensure transparent and comprehensive reporting of the intervention design, fabrication, and evaluation process. ²¹ The completed checklist is provided as Supplemental Material.

Results

Tensile tests

Tensile tests were conducted on two materials to assess the properties of 3DSF and identify optimal parameters for the printed bra. Testing involved stretching models in both vertical and horizontal directions.

After the tensile test, the models had a variable length between 61 and 78 mm. All the Thermoplastic Elastomer (TPE) models and some of the TPU models were torn in the horizontal direction.

The tensile test assessed flexibility, strength, and elongation capacity by measuring the force exerted on each model. The X-axis represents the elongation percentage of the model’s lengthening relative to the initial length. On the Y-axis, the force in newtons reflects the model’s ability to support weight, with a higher force indicating greater strength.

Figure 1(c) depicts the TPU tensile test results in horizontal and vertical directions. Lower eFactor correlates with greater model strength, requiring more force for tearing. At 100% strain for horizontal models, TPU50Y needed 58.5 newtons, while TPU110Y required only 23.5 newtons for the same strain. At 100% strain for vertical models, TPU50X needed 80 newtons, while TPU110X required 28.5 newtons for the same strain. In terms of flexibility, the linear region for all models is around 25% strain, marking the shift from elasticity to plasticity when the model reaches 1.25 times its original length. Stretching beyond this point results in a loss of mechanical properties.

Compared to TPU the TPE is weaker (Figure 1(d)). At 100% strain for horizontal models, the TPE pulling force of 35 newtons stretches the TPE50Y model, while TPE110Y requires only 15 newtons. The vertical models tend to tear before reaching 100% strain, with minor drops indicating instances of minor tears. TPE50X, the strongest model, tore under a 31-newton force at 58% strain. The weakest model, TPE95X, tore at 27 newtons at a 30% strain. These models exhibit an elastic region at approximately 25% strain.

Upon post-tensile testing examination, tear areas are visible. TPU models tore at the connection point of layers when stretched horizontally, while the vertical direction stretched without tearing. The TPE models experienced tearing in both directions (Figure 1(b)).

Compression tests

To compare the silicone and 3D-printed prostheses, both underwent a compression test using the Instron machine. The silicone prosthesis weighs 210 g, and the printed prosthesis weighs 77 g. Each prosthesis underwent three compression cycles. Figure 1(f) shows the compression percentage on the X-axis and the force in newtons on the Y-axis. While the pressure applied was similar, the silicone prosthesis required less force, indicating greater softness. The graph shows the silicone prosthesis curve remains consistent, while the printed prosthesis curve exhibits fluctuations, suggesting material non-uniformity. The results show that after about 40% strain, the silicone and printed prosthesis compression behavior is similar.

Wear test

Ten women tried on the bras for a total of 3 weeks. Based on participants’ initial feedback, the bra’s fit was good during testing, and provided a symmetrical look, especially when paired with a top (Figure 4).

Figure 4.

A woman wearing a bra without a shirt (a), and with a shirt on (b). The prosthesis is on the left side. The bra provides a symmetrical appearance. These photos were authorized for use by a written consent signed by the participant.

The average results of the participant questionnaire, obtained after 3 weeks, are shown in Figure 5. Participants had mixed experiences with the printed bras. Some participants, such as participants 3 and 7, found the bra to be very comfortable and a good fit. They also stated that the bra contributes to their feeling of femininity. In the open questions, participant 7 wrote that she enjoyed looking in the mirror again and that the bra helped restore her sense of femininity. Participant 3 wrote that she does not feel she is wearing a prosthetic. On the other hand, participants 4 and 5 disliked the bra; in their case, the fit was not good, and the bra was uncomfortable and even painful to wear. With that, most participants acknowledge the bra’s low weight, giving it a score of 1.6 for the question of whether the bra’s weight bothers them. Also, most participants did not report excessive sweating, which is associated with the porous structures of the printed bra. Feelings related to femininity varied, with three participants feeling a sense of completeness and normalcy, while others did not experience a significant positive impact.

Figure 5.

User study results—each average score is marked with a purple circle, and the participant’s number is displayed next to each. A line on the scale indicates the total average score.

Discussion

This study presents a novel approach to the fabrication of bespoke bras for post-mastectomy women. We utilized 3D scanning and 3D printing, leveraging the 3DSF technique to create a bra with an incorporated prosthesis that is also lightweight and breathable. We evaluate the mechanical properties of the materials by measuring the tensile strength in two perpendicular directions and the compression behavior compared to a silicone prosthesis. The results show that the extrusion factor significantly impacts the strength and flexibility of printed models in the tensile test. TPU excels in strength, providing durability and withstanding higher loads, albeit with reduced flexibility. On the other hand, TPE offers greater flexibility but compromises on durability. Considering the application for bras, where extreme weight loads are unnecessary, finding a balance between flexibility and strength is key. Future considerations involve strategically adjusting printing parameters for different bra areas and prioritizing durability in the chest and prosthesis regions, while allowing more flexibility in areas such as the back and under the armpit to enhance body movement.

In the user study, most participants reported a significant reduction in bra weight compared to their silicone-prosthesis bra. Regarding the bra fit, participants varied in their responses. The participant with pronounced body asymmetry found immense value in the customized bra, overcoming any minor discomfort for the comfort and natural appearance it provided. A participant with a smaller chest size, facing fewer challenges with existing solutions, found the customized bra less significant and preferred her usual options. Some participants were somewhat dissatisfied with the fit, possibly attributed to her scan being conducted with a padded bra. This highlights the need to refine the adjustment process, potentially through more precise digital calculations of chest volume.

The use of 3D scans in replicating the existing breast shape resulted in printed bras that provided a symmetrical appearance, satisfying most of the participants aesthetically. The lightweight nature of the 3DSF structure successfully addressed weight concerns, as reported by the majority of participants.

Beyond technical and ergonomic aspects, this study’s implications extend to body image, self-perception, and psychosocial well-being after mastectomy. Previous research has shown that women who undergo mastectomy often experience diminished body image satisfaction, loss of femininity, and reduced self-esteem, which can persist even with external prostheses.^10,22,23 Satisfaction with prosthetic solutions is closely linked to comfort, appearance, and perceived naturalness.^9,11 The current study’s findings—particularly reports of improved symmetry and restored sense of femininity—align with this literature, suggesting that design innovation can play a meaningful role in post-mastectomy recovery. Personalized, lightweight solutions that integrate the prosthesis with the bra structure may not only alleviate physical discomfort but also enhance body confidence and daily functioning. These outcomes resonate with studies highlighting the value of user-centered, aesthetic, and functional design in supporting emotional alterations following breast loss.^24,25 By integrating psychosocial considerations into technical design, this approach highlights how design research can contribute to holistic rehabilitation and improved quality of life for women after mastectomy.

Limitations

This study has several limitations. The sample size was small and determined pragmatically rather than through formal power analysis. As a design feasibility and user-experience study, the intention was to identify functional, ergonomic, and emotional factors influencing post-mastectomy comfort rather than to produce statistically generalizable outcomes. Future research should include a larger, more diverse cohort and employ power analysis to support quantitative comparisons of comfort, fit, and psychosocial impact.

Another limitation is the use of a custom satisfaction questionnaire rather than a previously validated instrument. As such, it provided valuable qualitative insights into user experience. Future studies should consider employing validated measures, such as the BREAST-Q or Body Image Scale, to enable standardized comparisons and psychometric evaluation.

In addition, some improvements are required to the bra’s design. Although most participants reported not experiencing excessive sweating, some still did, suggesting the need to explore materials and printing parameters further to improve ventilation.

Conclusion

This study aims to develop a customized bra that addresses the challenges faced by mastectomy patients. The varied responses highlight the crucial need for personalized solutions in bra design for these women. The rising number of mastectomies creates a demand for innovative solutions to address the challenges faced by women in post-mastectomy life. The approach of producing the prosthesis and the bra as one unit has advantages and allows customization according to the personal needs of each woman and the creation of perfect symmetry. The 3DSF printing method enables printing that simulates textiles and is also a soft and lightweight material for prosthetics. This study identified several areas for improvement in the 3D printing process, including the need for a more skin-friendly material and a more precise method of capturing the body geometry. The importance of personal adjustment for achieving perfect symmetry and positively influencing self-perception was emphasized, highlighting the need for adaptable solutions to cater to diverse needs. We hope that this research will raise awareness and encourage further exploration to improve the lives of mastectomy survivors.