On the cost itself, in fact, there are major costs to the development of a suitable design for a prosthetic. This is ongoing. This is why it's great that there is an ecosystem worldwide of researchers who keep working on this. I did have to absorb this. I had access through the Internet to a design that had been experimented on with many people before, so for me, the cost was really the cost of buying the material.
The material is filament. In fact, it's resin that is used in a 3-D printer. The filament, maybe I used $10 worth. As for the cost structure, it's very difficult to say because a lot of it is embedded in the design.
Then I needed access to 3-D printers. I was fortunate that I could access a free one. I didn't want to buy one, because they are too expensive for an individual citizen to buy. This is why we're advocating a sharing economy where expensive tools are available and can be shared.