The socket's rough dimensions when printed at 100% are Dia 21mm x 30mm long, so you can scale up or down to suit.
The trick here is to make sure that the thin walls of the hinge areas are fully defined in your slicer of choice.
I used Craftware 1.06 to slice these models with and extrusion width of 0.28mm so the thin walls were generated correctly. The Craftware setting file is attached.
I also include the .gcode files for anyone to view if they wish.
Assembly Instructions - Finger
The finger can be strung with tendon line (e.g. nylon) and anchored back to a wrist strap, or hand brace. Closing the residual finger will pull on the tendon line and close the digits of the prosthetic finger.
Thread the tendon down though the red path and then use a thin wire paper clip bent into a hook to grab the tendon and pull back out the end to tie off. Once tied off, thread the tendon back down inside the prosthesis and out through the small exit hole on top.
Thin wire paperclip bent into a hook tool.
The reinforcing ring may or may not be of use, depending on how well the prosthesis fits the residual finger. The ring will help stop the flexible side walls of the prosthesis from collapsing when the tendon is pulled.
The bracer can be adjusted in Customizer for your hand size and which partial finger/s you would like an attachment for.
It is designed to be printed flat in PLA and thermoformed around the back of your hand or wrist
Straight off the print bed and ready for thermoforming.
Submerge in hot water until soft, use tongues/spatula etc to remove and form to shape required shape
Fitted around back of hand
Provides anchor point/s to attach a tendon line to.