When I was 7 I tried to move to sell camping space in my parents backyard. I made up a name(no idea what it was) Made a sign, figured out pricing, and was out by the road with a table trying to get some people in. My parents shut it down though. No love for a young business on the rise. Hopefully trump makes America great again, so that nobody else has to get shafted like I did.
I was gonna get rich damn it.
Other than that I would say all the stuff I built in the yard like an 18' tall wooden drop in ramp, mini ramps, 1/4s etc, but they got pretty used to that stuff early on and ignored it.