Science Buddies: "Ask an Expert"

I am trying to figure out the best way to design and build a prosthetic hand

Great! What is the scientific question you are asking related to a prosthetic hand?

The first thing I would think about is to find a website that has all of the neccesary materials to make that.

I am trying to figure out the best way to design and build a prosthetic hand

Words like "design" and "best" tend to be things that engineers do (coming up with designs and analyzing designs).

If you intend this to be an engineering exercise, then proceed like an engineer and ask questions like:
What does it have to do? What would you like it to do?
What do you want it to look like?
Questions liike these lead to "design goals or requirements" and allow you to evaluate different concepts and designs against the goals or requirements. The subtle difference in the questions between "have to" and "like it to do" differentiate hard and fast requirements and nice to haves. If you have too many "must have" hard requirements, the problem might not be economically solvable in terms of time or money.

So what requirements are you thinking about?