i would try springs out of a ball-point pen or you can get spring assortments from an auto shop.
by the way, on the diarama, i always thought it would be cool to do one of a drive-in movie scene. And then on the big screen you could a have scene from Bullitt or American Graffiti or something on there.
p.s. don't forget the popcorn!
"Well done is better than well said." - Benjamin Franklin (1706-1790)