DS likes any hands-on construction project with a design element. Things I'd like to do with him when he's a bit older:
-Finish a basement
-Build a deck or patio
-Rebuild an old car
-Wire the house with a central control panel for blinds, media, temperature control, etc.
-Design and plant a garden and irrigation system
-Build a computer
-Make various machines/putter with electronics

What is to give light must endure burning.