3 d printing project

Hello everyone,
I am a young French physiotherapist passionate about 3d printing.
I have a printer Ultimaker but I am a novice in software 3d designs.
My project is to create a upper limb prosthetic for one of my patients.
Does anyone interested would be to help me in this project because I want from an open source model, improve the appearance, usability and make it as pretty as functional prosthesis.

do you have any reference drawings?