*pats your shoulder* Perhaps he is going to use these projects as a means of deciding a career path? Then at least it will be somebody else's problem if he is digging in the wrong place?

In the meantime, do not take him to try out heavy equipment...ever...and I am trying to think of ways to deter him from digging up your backyard- I have visions of large pits with THINGS at the bottom..or just one of you falling in...

Fortunately when I tunneled I was only allowed to do it in mud or sand - we have trees that my father would not let me disturb - or the grass - that would have led to yelling.

Hmm.