Besides gaming, obviously, I would have to say 3D printing. I got a 3D printer back in april after wanting one for years, and I absolutely love it. There are millions of 3D models you can download and print, but for me, the real fun has been learning som basic 3D modeling and designing my own things. So far I haven't really made anything that complicated, but It really is amazing to see a problem around your house, and a few hours of modeling and printing later, having the solution in your hand.
Part of the hobby has also been collecting different kinds of 3D printing filament, which is the actual spools of plastic you use to print. There are a bunch of different materials that have different use cases, and thousands of different colors.