The standard Rubik's cube and many of its variations aren't too hard once you know a few basic principles. I gave a 7x7x7 cube, a teraminx and various other twisty puzzles which aren't too hard, although they may take a long time due to the number of pieces. This one though, the "curvy starminx", was much harder to wrap my head around. The sequences aren't actually very complicated though in the end.
This didn't take much time away from Stella, but writing music has!
https://soundcloud.com/robertcwebb
There's too many things to work on and not enough time.