The difference between the two was probably one of the first things he learned.

A few years back, I noticed my DSL modem, router, network hub, etc. were around 5-6 inches wide. I figured if I could take the guts out and put the boards in custom enclosures, I could convert an old PC case to a mini rack mount, with a lot of the cables contained inside. Never came up with an enclosure solution I liked, though. Most of these devices are powered by wall warts that feed DC current, the challenge is picking devices that take 5 or 12V (there's a lot of stuff out there that wants 7 or 9V, although that can be done if you want to get creative).