Not my child but my brother. Fan of messy sensory things, searching, sorting and physics e.g. floating spinning gravity etc
Finding hidden things in the dark with a torch, when he was little it was finding trucks and cars, when he was early teens it became those glass pebbles.
Finding loose change buried in sand with a fork or a sieve or chopsticks (pirate treasure)
Baby sized paddling pool with cornflower water mix or paint or sand or ice cubes or rice krispies, shaving foam, frozen peas, uncooked rice or pasta, mud etc sometimes a combination
Water toys
Potions
Big roll of paper sellotaped to the walls for doodling on
Ramps that go down the stairs, bigger the better for rolling things down or cars
Making parachutes for different sized toys to then race them off the bannister, developed from a love of throwing anything he could off the bannister
Making dens with the sofa and blankets and cardboard, (bulldog clips are amazing for keeping sheets up and attached to clothes airers.) He wanted nobody else in these
Outside, he liked going to little rivers (if no other families close by) to sit in or float toys in or make rope swings near.
Treasure hunts in the woods, usually chocolate coins because he liked pirates
Digging holes in beaches
Diverting water in beaches by digging tunnels
Hoovering, the neighbors would let him come and hoover round their houses too, and cleaning glass windows with the spray (just water spray before he could be trusted not to drink it)
Painting walls, he used to use his pocket money to save up to repaint the bedroom, every summer for 8 years between 8-16
Whittling
Paper mache goo, just sensory not making anything.
Testing the power on rechangable batteries
Sorting buttons and beads
Shaving foam and the squirty bath soap, and frozen flannels.
Roundabouts, swings, slides, mostly accessed at night or really early in the morning to avoid people before he got older and could handle waiting for his turn etc