Something that you're interested in that isn't really a popular interest/hobby?

I paint rocks. Like... rocks. I mean, I guess I should say that it's on the rise because there are now facebook groups and all kinds of stuff for it but it wasn't always a fad lol...

But yeah, you paint rocks with whatever pretty thing you can manage at your skill level (mine is low so I do a lot of ladybugs) and then hide them around town and other rock painting people find them and do the same. It's fun finding other people's art and them finding yours. I had a girl post one of mine on the FB group a couple days ago because she'd found it and it's pretty cool.

Less popular interest would be that I roleplay. Calm down creepers, not that kind of roleplay. I am part of a writing group that does a Hogwarts (yes, Harry Potter) roleplay message board in which you play a student and go through the motions. It's fun and addictive and I've been doing it since I was too young to be any good.

I don't have any like that :3

Retro computers.
That's pretty popular in the US, but not so much in Germany.

I make collages out of old Time and Life magazines.

Meditating

idk, i kind of do a little bit of everything, it's popular with some people. everything from cosplay to making my own hair accessories. to furniture restoration and painting.

Operas based on revolutionary novels.

Beeeeen tickled with a pencil

Playing the ocarina.

Caving and scuba diving.

art history n.n

History.