My dad was a pilot and engineer, and we built many things together in my childhood (go-carts, computer video games, an automotive speedometer, more).

But there was one thing that I always wanted to do with him: build an airplane. As a 13 year old, I found different plans from vendors, created a budget, put together a basic timeline, but could never convince him to do it.

In fairness, building a plane is a huge multi-year commitment, and almost certainly more expensive than buying a used Cessna. But the price is not completely out of reach for many folks (<$100k). The real draw is the amount you learn during the process and seeing your handiwork.

I'm still sad we never did it, but it was a big ask of a dad with a full-time job from a twerp son. As a consolation however, he did buy a small wing-section kit and we got to rivet a few panels together over a weekend. First time I ever used rivet fasteners!