To fill the last hole in the panel, I decided to add a knob of my own. The ThingamaKIT is designed to be tweaked and even includes instructions for suggested modifications. For my modification, I wired a 100k pot to a few alligator clips and poked around the circuit board for unique sounds. I discovered a modification that worked a little like a waveshape control for two of the three oscillators, adding a raspy squeal when the knob was turned. Once I was happy with the result, I took off the clips, soldered it up, and mounted the pot into the center hole.