<p>I am currently working on parts for a custom prosthesis.</p>

<p>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.</p>

<p>The main concerns I have are:</p>

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

<p><strong>Which materials can you recommend?</strong> </p>

<p><strong>Any extensive data (from testing) would be greatly appreciated.</strong></p>

There are printers designed for medical use, and the manufacturers supply them with varying levels of
certification and testing
, however I've not seen a filament manufacturer certify their material as bio-compatible separate from the printer. The printing process changes the material slightly in the best case (and significantly with poor temperature control or badly set parameters), so even if bio-compatible filament were found, the resulting product might not achieve the same level of bio-compatibility.
If your intent is to use hobbyist level machine for medical purposes, you might simply want to use an interface, such as a sock or a molded/cast polymer that you know to be bio-compatible between the printed part and the skin.