Marble Races with a cheap pool noodle (occupies the kids for hours.) Did this, but instead of cutting the pool noodle, the marble is small enough to fit inside the full noodle to roll down. Then can use the noodle for other things too!
for hand sanitizer! LEGOs suspended in a liquid soap dispenser. Fun to put out at a LEGO party or everyday use in your kids' bathroom! I'd probably search for a cuter dispenser, maybe more geometrical, but still such a cute idea!