Enjoy those years. My mom bought The Dangerous Book For Boys for my son when he was younger. He's 19 now, so not much interested in that anymore.
When my oldest daughter had a project on simple machines, we built a toothpaste squeezer.
It was a block and tackle with 4 parts of line connected to a clamp on the tube.
Turn the hand crank and it squeezes the tube between a ramp and a roller.
We've dug clay out of a creek bank to make a mud hut.
Those projects were a lot of fun.