Figure 5.

(a) STL model of the scapula (left) shows that the fabrication (right) created by using a bottom-up desktop SLA printer (Form 1+; Formlabs, Cambridge, Mass) does not include the glenoid cavity (arrows). Such failures occur owing to dirty optics or mechanical forces exerted on the model during printing. (b) Printing failure involving a material jetting printer with two print heads (Objet Connex 2; Stratasys), each loaded with one material. The black cube at the top far left corner was printed with 100% of material 1. The cube in the far right corner at the bottom was printed with 100% material 2, with the cubes between them printed with mixtures of the two materials in different proportions. Use of the 100% black material in a faulty print head led to a depression (red arrow) where the model height was 19.54 mm as opposed to the model design height of 20 mm. The model created with the fully white material measured 19.99 mm in height. The cubes containing increasing amounts of the material printed with the correctly functioning head have progressively less error.