The same can be said about boating, you should be wearing a life vest anytime you are in a boat and always acting in a safe manner.
The town I live in has a boat building/ racing contest every year. The challenge to this contest is the materials you are allowed to use as well as the ones you are not.
The materials include:
1) 1 sheet of Plywood (any thinckness)
2) 2 8 foot long 2X4's
3) 1 Roll of Duct tape (Essential for almost everything I build)
4) 1 Lbs of fasteners (I chose 1X6 rough thread drywall screws)
You are not allowed to use Glue, Epoxy, Chaulk, Silicone... In short NO adhesives at all.
The boats may be decorated with paint and will also be judged on theme and appearance.
I had paint laying around so my total cash outlay was less then $50
Here is a link tot he Yahoo groups that I got the plan / desgn from along with some great advice. http://groups.yahoo.com/group/onesheetwonders/