I wrote a song that needed an upright bass.
I was quite pleased with it. I didn’t have an expensive sample library with the Upright Bass sound in it, so I grabbed a coffee cup, a pencil, a paperclip, some sticky tape, a rubber band, and a pocket knife.
After calculating the correct hole size using a formula related to a helmholtz resonator and cutting it out with the pocket knife, I had the instrument I needed.
Here is a picture.
Unfortunately, the Coffee Cup Bass is almost impossible to play. So I sampled it and played through a MIDI keyboard.