I borrowed an idea from my friend Mads Hobye for my enclosure. Mads founds these sleek boxes at the container store and used them to make project enclosures for the various musical instruments he's built. These boxes are particularly convenient because they have a bevel around the top that allows you to easily mount a 5mm acrylic front panel.

I used a laser cutter to cut out two USB ports (one for the Arduino and one for MIDI out) in the bottom of the enclosure. Then I used a drill to make holes for two pots, a power switch, and a charging jack.

I laser cut a front panel from translucent white 5mm acrylic so that it would snap fit into the wood box.  This has stayed fairly secure so far, but I think it might be made better with some kind of magnetic snap.