Here's my custom pi box.
This will be my web server sitting on my desk, so
I wanted something a little on the pretty side, but
still wanted to see the circuit board inside.
Some pine scraps, a piece of Lexan for the cover,
a couple of coats of Polyurethane and Zingo!
A pi box!
The toggle switch cuts off all power to the box.
A 12 volt, 1500 ma cube supplies the power. The UBEC
drops that to 5 volts at a maximum of 3a, more than enough
for the Pi. In the pic, it's reading 5.23 with only the
voltmeter connected. I expect it will drop a little bit when the
Pi applies more of a load to it. (Still don't have a power plug so
I can't actually power up the Pi yet. It's on a slow boat from China.)
The push button will eventually be hooked up as a "graceful shutdown"