I'd love to have the tools and know-how to design and build my own stuff. I would imagine that most of the guys on this sub-forum feel the same way. At work we have a machinist who's done some minor welding jobs for me and is VERY capable with the fabrication side too, but as far as making actual component parts, that's something that he has neither the time or interest in doing for me. He does work related stuff for us all the time and I'm always impressed with the quality and detail work he can do. I don't think I'm artistic enough to be a good machinist, but I may give it a go to a limited degree someday anyway. Bummer though that you seem to need quite expensive tools and a decent sized shop to do the really fancy stuff.
Oh, and you've GOT to post some pictures of everything that you mentioned in the OP, especially the sprocket. =)
-Jeremy