D-I-Y Project Enclosures?

cg asks: "Like many others, I come across a cool hardware project that I feel like getting into from time to time. I can usually find the hardware I need and get things working. My biggest problem is enclosing the final product. I've used everything from cheap RadioShack project enclosures to cardboard boxes. What I want are suggestions on how to build professional quality enclosures for these devices (from remote control size to small PC). I am not worried about it passing FCC standards, but asthetics are important."