This video shows the function of a partial finger replacement that can be customized via inputing measurements into a free web-based application (Makerbot's Customizer). Digital files for the parts can then be downloaded for free and either produced via a home 3D printer or emailed to a company that offers 3D printing services.
The instructions and files can be found here:
http://www.thingiverse.com/IvanOwen/designs
The device was developed & fabricated using a Replicator 2 provided by Makerbot.