Have you built your own components? I got a commuter rig from a mailorder mike operation and would love to replace the stem with something I've made.

I am getting into some CNC/casting/woodworking was curious if people have fabricated their own parts. I've always wanted to at least mockup my own parts in wood. 

But I wonder: has anyone gone the next step to either cast parts in smelted aluminum or CNC'd them out of billet aluminum? Or even kept the part wood and placed the proper metal fittings into it so that it could function like it's metal counter part? 

I know it must sound like like I'm taking crazy pills but I can't seem to get this idea out of my head...
There are people who are making custom parts for bicycles, also stems in particular. Whole bicycle frames as well.

But it is a non trivial craft that takes time, practice and determination to master properly. Not to mention that failure of some parts can cause serious injuries, so tread carefully.