ORIGINAL: cumquat
it bugs me when people say the dont have the tools to make their own parts. the simple fact is that you dont need a cnc machine, plasma cutter, tig welder and all this really expensive equipment to make your own parts. its likely not the tools you lack, its the creativity. i can give you very simple designs for shock towers that only require a drill with bits, a pair of metal shears (aka tin snips) and a file to smooth the edges. i am presently designing a custom chassis with suspension that can be made with a drill, vise (even vise grips will work) an angle grinder (most of us have a dremel which will work just as well, albeit slower), misc. hardware and ~$30 worth of steel strip (1/8''x1/2'' and 1/8''x3/4''). i am not using any expensive cad program either, i am using the free version of google scetchup 8.
Making a chassis is one thing. I could do that with my Dremel. Probably will eventually, I want to make a nitro RC that's got a front mounted engine that's centered left-to-right. Making diff cases? Not quite so sure about that. If the holes don't line up just right, if the halves don't seal, then it all goes bonkers.