Touch Buttons
I find touch buttons the easiest decently-looking controlling element for DIY. The TTP224 4-channel board costs 0.60USD on aliexpress. The board is connected to 4 digital inputs of arduino, powered by 3.3V.
The four touch pads are made of standard Allen (hex) key black M3 bolts for a few cents.
On the inner side of the case the bolts are screwed into M3-threaded copper strips 6mm x 10mm. First cut the thread, then grind off to proper width. Short wires were soldered to these copper "nuts" before installing them into the front panel groove.
Make sure the two bolts at the bootom of the front panel are as short as possible so that they do not touch the PC board when assembled.
