BeatBox DIY DJ Controller

I'm sorry that I didn't take any pictures of the project when I first started, but I would love if the DJTT community could help me finish this off. My goal is to create a MIDI controller with 6 arcade buttons and one LED switch to accompany my Numark Total Control. I have already picked a small lunch box for the case and drilled the holes in which I inserted the arcade buttons. To make sure the buttons do not rattle when used I applied silicone tube filling. The ends of the buttons have been soldered to lead cables and secured with shrink wrap. The switch is also mounted on the controller.





The next step for me is selecting a control interface, or brain, to run the BeatBox. I am unsure on what brain to buy and how many connections I will need for this to work. I am considering the U-HID Nano, but I an not sure if one pin has both the positive and negative for one arcade button or not. This is important for me because the Nano comes with only eight pins, while I will have a total fifteen lead wires to be connected (12 from the buttons and 3 from the switch). If anyone has any experience with custom MIDI controllers, can you please suggest what brain I should buy and why? Thanks, much love!