The Teensy was chosen as the brains because of the way it handles USB. Not only does it have native USB, rather than the FTDI USB-to-serial interface that turns making use of the port a series of work-arounds, but as you’ll see in the code the MIDI library makes writing the firmware a trivial pursuit.
Caveat: I found out later that my scaling of the sliders is off & doesn’t allow for full travel in Traktor. Since the controller is away at college with my son I haven’t had access to fix this. I’m certain that it’s just a matter of changing the scale factor, though.
The parts list:
Teensy 2.0 CPU from PJRC
7-inch sloped enclosure from iProjectBox
Sanwa Arcade Buttons from DJTechTools
Joystick from SparkFun
Slide potentiometers from SparkFun
Pot knobs from SparkFun
Panel adapter cable from AngledCables (When I made this 2 years ago AngledCables was about the only source for this adapter cable. Looking online recently I've decided to purchase some from AdaFruit at a much better price.)