I'm looking to build a small CNC router or mill for hobby use, and to be frank I'm not sure which machine to purchase plans for or whether I should bother with plans at all. Here are a few specifics: I'd like to have basically a small multipurpose machine, capable of 1/4" or larger ply (1/4" single pass), plastics, and aluminum. It would also be nice to be able to do hobby PCB milling. I'm figuring the PCB milling and the ability to handle aliminum are going to be the difficult specs, requiring a pretty stiff and accurate machine. Cutting envelope would be something like 1' x 2' x 4".
So I ask: bilge brain trust, do you have any suggestions, advice, pithy anecdotes, or dire warnings of which I should take heed?