geekhack for keyboard group buys
my various private torrent tracker forums, ptp, red, etc

I'm a scientist who loves memes and shitposts, so it's quite the smattering.

the 195 and 196 communities are amazing. extremely random memes and pics.

shitposting is too notch and /c/memes is good too.

I like the no lawns one over on solar punk, and some other environmental ones

This isn't niche at all, but gbatemp is fantastic. Lots of emulation, modding, romhacking, general gaming discission, etc.

3dprinting for sure. Friendly, informed and fast replies. Like it there.

I love all the gaming and nerd communities. Cause forums on my favorite games is my favorite part about Lemmy. /c/legendofzelda /c/starwars /c/stormlight /c/playstation

Sailing Anarchy for all things related to sailing. There's a small subset of folks on there that are very toxic, but it is the best place for extremely technical content.