Once upon a time as a den leader I suggested to the pack leader near the end of the derby that he should give an award to the boys who did their cars by themselves, which is what I did as a kid.  Looking at the cars I thought for sure there were one or two that were independent projects.  We were already giving out awards based on design and theme and all that so that everyone would get one which is cool even if they didn't place.  So anyway he agrees and announces, "now raise your hand if you did your car all by yourself, we have an award for you".  Not one single hand.  So I guess I was wrong.  Some dads aren't much help.

But seriously, the boys should have the experience and pride of doing their own maybe after learning a few tricks.  Two different competitions would do it.