Here's a neat little gadget I briefly got out of storage the other day. It's a cassette 4-track machine from the mid-'80s, essentially a whole little recording studio in a box that uses a standard cassette tape as its recording medium. This was a pretty common genre of device around the time, and they're all pretty similar; this one is on the lower end of things (notably, it can only record 2 channels at a time) but you could just about record a demo on here.
Like all cassette 4-tracks, it runs the tape at double speed and records on both sides at once, so that C-60 actually only gets you fifteen minutes of recording. It's got a neat partially-electronically-controlled transport, which lets it do stuff like that "zero return" feature (which stops rewind when the tape counter hits 0, so you can easily go back and forth over the same section a few times) but did unfortunately need a bit of work when I got the machine; my recollection is that a plastic piece that holds the tape head up disintegrated and I had to replace it with a 3D-printed replica. As is required for a studio machine, we've also got per-track erase and a very responsive pause button.
This machine unfortunately isn't really useable at the moment, it needs a recap and until then you're doing all your recording with a pretty obnoxious high-pass filter. Might be something to look at, though, I believe the electronics aren't too sophisticated in there.