Asklemmy

Not me, but my wife. She collects kpop cards. Apparently the bands have a random card of one of the members in the albums. Theres a whole trading and selling market for them.

I repair and upgrade classic video game consoles. RGB modding NES, Adding HDMI output to a PS1 etc. Sometimes in the case of some NEC consoles like the Turbo Duo R, I'll buy ones that are totally hopeless (capacitors in these thing leak like crazy) and pick away at it for months, I've had some janky looking consoles but I've brought them back from the dead. Always satisfying when then work again.

I genuinely love brass band. It is a not terribly known form in pop culture (even among "classically" trained musicians) but that shit is awesome.

I’ve recently returned to wanting to get into guitar amplifier repair and design.

I have a pair of amps that i want to diagnose some particular problems and perhaps design a new pcb for or build out whole new ones

I don't think it's super obscure, but I home brew beer and it's a hobby where you can really go deep into the technicalities of tweaking recipes, building equipment, and just the overall process in a way that would probably bore the average non-brewer to death.

For me, probably insects. I've been fascinated by insects when I was little, and honestly I feel like I've been getting back into it recently. I started keeping a mealworm colony recently so that I wouldn't need to buy mealworms for my frog (it was really more of a practical decision than an interest in having a colony, but mealworms are pretty cool nonetheless)

I've been considering getting a mantis and/or some rhinoceros beetles, but I'm not really sure where I would be able to get the materials required to set up terrarium for them

I like to wonder around the forest singing.

That and rock climbing but like traditional and aid climbing in the alpine. Most people lose interest when I start talking about various knots and their attributes in different situations.