I am currently working on parts for a custom prosthesis.

My main concern at the moment is to find biocompatible materials that can be 3D printed from a UP or a Reprap.
The piece would need to be in contact with the skin for extended periods of time, probably around 17 hours a day on average.

The main concerns I have are:

 - Skin reactions caused by prolonged contact
 - Skin reactions and bruising caused by friction
 - Degradation of the materials due to prolonged exposure to skin secretions and sweat
 - Risks of toxicity in the compounds generated by the aforementioned material degradation

**Which materials can you recommend?** 

**Any extensive data (from testing) would be greatly appreciated.**