At 8 years I recycled filesystem directories. I didn't know you can create new folders, so when I needed one I grabbed a random one from C:\Windows, moved it to my desktop and deleted its contents.

When I was a boy all we had were high-voltage vacuum tube electronics, it was fun.

I was doing that at three or four and was reminded of it constantly for the next ten years or more. (I actually raised the subject on my mother's death bed.)