We cover a lot of high-tech medical devices here at Medgadget, many of which often require a huge spend just to make it to a commercial release. Unfortunately, these costs frequently result in prices which can put many treatments out of the reach of many patients. 
Prostheses are no exception, and it was the prohibitive cost of new prosthetic fingers that set Richard Van As, a South African woodworker who lost four fingers while operating a saw, on the road to finding a lower cost solution for his lost fingers.
Richard contacted Ivan Owen, an American designer based in Washington state who had previously developed a basic mechanical hand, to develop a low cost, open access DIY prosthetic finger design as an alternative to existing solutions. Richard and Ivan have been collaborating on the project over the Web and through the post and have been publishing their progress on the project page.
The first iteration of the prototype system comprised pieces of an Erector set, hair ties, zip ties, leather scraps, velcro strips, string, moldable wax, and rivets. At its core the prosthetic is a formed hand mould and a simple system of cables, levers and pulleys. The prototype is demonstrated by Richard in this video:
Richard and Ivan have been publishing all of their designs online and the project is strictly non-profit. Their aim is to make their finished prosthetic a real, low-cost DIY reality for many people who can’t afford commercial prosthetic digits. The project blog and design page alone are a great example of focused problem solving and the iterative design process necessary for many devices.