Haven't thought about those competitions for years.
I remember in high school hearing the announcements, and know it was completely out of my experience to attempt, but they were interesting. Basic 'how you cram a human body into a vehicle' but your imagination's the limit there after.
I do remember they made a big thing of how you could make taillights out of toothbrush handles, which were mostly clear colors at the time.
Do realize that the Fisher Body engineers created a lot of the same thing, and a few even made it to cars, INCREDIBLY toned down.
Doug
Edit:
That's already the case on a small scale, thanks to replica cars and kitcars.
If you think about it, on a bigger scale, the same thing is straight from design to customer, with Chrysler's Prowler, Viper, and PT Cruiser.