Sometimes I play on very cheap toy keyboards (they can be circuit bent).
One thing that they often miss is a sustain pedal like on real pianos.
So I attempted to create a "fake" sustain pedal in pure data in a very cheap way : it samples a tiny chunk of audio and repeats it while the pedal is held down.
It kind of works but there is still one weird thing : on a real piano if you press a new key while the pedal is already held down you expect it to be sustained as well which is not what happens here.
Also I initially wanted to embed it in a Raspberry Pi before I realized there was no audio in on it so I stopped working on that, still I'll keep that in mind, it was funny to use.