I know this barely qualifies as a hobby, but I’ve really gotten into lava lamps lately. I’ve had a nice red/clear Oozy Goo lamp for years, and I just bought a larger black/clear lamp with a gunmetal base on eBay. One thing that does make it a hobby is that there’s an art to restoring them. My new black lamp was cloudy, and running it for a week didn’t help. I found the Oozing Goo forum (google it and go to the top hit); there I learned the right way to replace the clear fluid.
I went to my son’s apartment and he still had the 17” red/clear lava lamp i gave him when he was around 10. I’m envious of his lamp’s flow. Pics of our lamps for reference.
You guys in the UK are lucky, you can buy from Mathmos. I ordered a 27” lamp from lavalamp.com, got my fingers crossed that that one will work well.