Table 2. Suggestions on how to choose printing parameters for fused filament fabrication (FFF)/fused deposition modeling (FDM) 3D desktop printers.

Different 3D printers and print environments may have subtle effects on the values of parameters needed in the workflow (step B1. Generate gcode for 3D printing). We therefore present the results of systematic parameter exploration (over 50 prints), to assist in empirically choosing and adjusting 3D printing parameters. Where noted, parameters may involve a tradeoff between speed and smoothness of the print, the choice of which may depend on the use of printed object. In parentheses we include the parameters that we have found to produce usable objects in the time needed (<1 day) reliably.

Parameter	Characteristics for reliable prints	If parameter is too low	If parameter is too high
Build Plate Leveling	Extruded filament is flattened, consistently adhering with an even height over the whole build plate (Gentle grip on piece of paper)	Filament will be overly round and adhere poorly to build plate. Print may curl or warp upwards.	Filament may extrude minimally or inconsistently, building up in the nozzle. The motor may click if there is too much resistance to flow.
Filament selection/quality	Filament width and adherence to plate and other layers is consistent, especially on support layers (StellarLabs PLA filament)	Filament width and adherence to build plate and other layers may be too variable, causing the filament to curl up and the print to fail.	n/a
Extruder Temperature	Smooth filament extrusion with flow primarily during printing (210°C)	Filament will not melt and extrude, and motor may click if this causes too much resistance to flow.	Filament will extrude during the preparatory printer warm-up, before the actual printing begins. Higher temperatures also presumably increase the risk of a fire hazard.
Build Plate Temperature	Good adherence of the print to build plate, but with relatively easy removal of the object from build plate at the end of printing (50°C)	First layers will not adhere well to the build plate, curling up and possibly causing the print to fail.	Object will adhere too strongly to the build plate, making it hard to remove at the end. Additionally, the first layers may discolor and widen out slightly on the build plate.
Shells	Appropriate balance between overhang support and print time, reflecting the purpose of object (1 shell)	Overhanging elements may be likelier to droop, but fewer shells yield a faster print time with less filament use.	More shells decrease drooping of overhanging elements and make the object more resilient to aggressive post-processing, but at the expense of increased print time and filament use.
Infill	Appropriate balance between resolution and print time, reflecting purpose of object (2% brains, 5% skulls)	Less infill yields a faster print time with less filament use, but the final object is likelier to be more fragile. Less internal support can cause also some holes on flatter, internally overhanging higher layers.	More infill increases print time and filament use when there is significant internal volume to the object. These costs affect brains more than skulls, due to the thinner nature of the skull volume. Final objects with greater infill are likelier to be sturdier, with more support for flatter higher layers that have an internal overhang.
Feedrate/Travel speed	Appropriate balance between resolution and print time, reflecting purpose of object (70 mm/s, 100 mm/s)	Higher print precision, slower print	Faster print, but decreased print precision. If too fast, filament extrusion may become variable and not adhere to prior layers. Fast speeds may also cause misalignment between layers and may cause the printer to vibrate excessively.
Raft & Support	All elements supported with easily removed external supports (Raft + External Support)	Printing without supports may cause overhanging elements to print in the air and/or adhere to nozzle, possibly causing the print to fail.	Full supports increase printing time, filament use, and post-processing time to clean and remove the supports.
Layer Height	Appropriate balance between resolution and print time, reflecting the purpose of object (0.3mm)	Smaller layer heights yield a higher print resolution, but slower print. The lower limit is limited by printer specifications.	Larger layer heights lower the print resolution, but yield a faster print. The maximal value is limited by printer specifications