This is an open source project for application of cycloid needle reducer. The target is of relatively small capacity application.It is possible to use this model in envelope less than 50 x 50mm.Such as wrist drive or enven smaller location application. It is possible to print all the parts of the Cycloid needle reducer by 3D Printer.Of course,the low surface accracy quality will affect the rotating stability somehow. However, you can see the rotating ripple is a fairly small value. The peak to peak displacement is around 1micro if all parts are made in steel. Of course,plastic will make the deformation a little bit larger at the same load level. No micro geometry is available and practical applied in print procedure. So a reasonable clearance will be very sensitive and important. In term of durability, prediction method will be given in the following documents(no timeline and see condition). Only geometry model will be built via Freecad and obj model from in-house design system, to provide input for 3D print process.Metal piece will have much better durability performance if applying grinding method. The shortage of high accuracy steel parts are heavier and more costy than print one. While the advantage is of high transmission accuracy with much smaller clearance being applied. Again. plastic parts here will be assumed.Good luck!