I would definitely agree with the birdhouse. However, even though you can buy a kit at the big box stores I would actually buy the tools separately and just get one cedar fence picket.

Cedar would be easy to cut with a hand saw and to drive nails into.

You would need a good short hand saw, hammer, nails, drill, 1/2” drill bit, 1” drill bit, square for marking the wood to cut, 1/2” dowel, 6” x 6’ cedar fence picket.

Then he could use his imagination from there. I just started tinkering in my dad’s shop right around his age.

If you burn a few, that’s how you learn.

Let me know if I can help any more.