The growing availability of 3D printing has made it possible for end-users to manufacture prosthetic devices tailored to their individual needs. For example, Project e-Nable (www.enablingthefuture.org) provides parametric 3D-printable prosthetic hand designs. However, the e-Nable hand is an assembly of standardized parts, customized via rigid-body transformations. For cases of trans-tibial and trans-femoral leg amputation, the required prosthetic must blend mechanical parts with a socket that conforms to the shape of the residual limb. The socket design also plays a critical role in minimizing pain by distributing the significant mechanical stresses to appropriate anatomical locations. As a result, design customization is much more challenging.