This week mine was homemade soda. Fermented sodas, citric acid + bicarbonate sodas, different juices and flavors like lime + lemon + cherry and pomegranate or mango peach or cola (homemade knock off)
Emulating Switch games on my phone. I've got a Switch, and I'm emulating the games that I own, but because it didn't immediately work on the phone, it's started that little obsession.