Tile mosaics would be really fun (I never even made a stepping stone in grade school), but it’s way too messy between mixing up cement and pouring it out into molds of some type in order to stick the tiles into, let alone smashing up a bunch of big tiles into shards to use for such a project, to be feasible atm, ditto for anything dealing with plaster.

Paper mache, a medium I haven’t messed with since middle school, would also be really fun to pick up again some day, but just like plaster and tile mosaics/stepping stones, it’s also too messy to be feasible right now; not only will you have paste dripping everywhere due to the nature of paper mache as a medium, but you’re also going to at least be up to your wrists in it, possibly up to your elbows depending on how big you’re going, but you’re also basically playing in slime all day with that project which is why it’s as fun as it is.