This is just a small project box I made for prototyping various projects. It works great for the Arduino Synth. I used a small enclosure I got at RadioShack.
I managed to fit
6 x 50kohm pots
2 x red LEDs
1 x rgb led
1 x power switch
1 x 3 pole switch
2 x momentary buttons
2 x speaker wire terminals

Step 1: Mount Everything

Basically I just fit everything where I could, drilled holes and mounted everything.

Step 2: Wire It Up

I soldered solid core wire to all of the components. The solid core wire fits perfectly into a solderless breadboard.

Step 3: Coil the Wires

I coiled all the wires around a permanent marker to make it easier to get them all to fit in the box.

Step 4: Add an Arduino and Have Fun

I managed to fit a small solderless breadboard with an Arduino nano and everything I needed to turn it into the Arduino Synth. I connected a 9v battery to one of the speaker wire connectors and a small 8ohm speaker to the other.