Subject: What materials are best for Rubber band Powered Cars!

I recently came upon a Physics day challenge prepared by Caltech students for a 
local high school.  They were requested to build a rubber band powered car that 
would go fast down a track with a guide wire in the center to keep the car on a 
straight path.  The trick is the car must carry an egg and there is a brick wall 
that the car will hit when it reaches the end of the track.  I have had my 
students build simple rubber band cars with spools.  We have to add parts to a 
car that would hold an egg with the following limitations.  The car can be no 
longer than 45 cm. long and no wider than 20 cm. wide.  I have had a track built 
with those specifications in mind.  I need to use simple everyday materials that 
a 7th and 8th grade class could handle.  What materials do you think would be 
best for this project considering the fact that the egg will be placed some 
where on the car in a styrofoam cup that is cut down to 3.8 cm high.  I would 
appreciate some help in this area to better guide my students to insure a great 
outcome.

Re: What materials are best for Rubber band Powered Cars!