Yesterday, I got a Korg Monotron Delay. If anything can be said to be a synth fidget toy, that might be it, or at least a good start.
Gotta say, though, it's really, really noisy, which might actually be by design, at least in part, and very unshielded. It was picking up a bunch of digital hash from something which came and went as I moved it around. Turns out, it was my Airpods Pro.

Tuta
in reply to Mark Wyner Won’t Comply • • •