Get him something to take apart and put back together.

I don’t know your son’s age so some of these may not apply.

1. Lego

There are sets designed for every age.

2. Bicycle

3. Mini-bike / moped

4. Leathercrafting

5. R/C car, boat, airplane

6. Capsela building sets

7. Rubik’s cube

8. Jenga

Game that doubles as a puzzle that doubles as building set

9. ATV

10. DIY computer build kit