Summary

A leaf spring frame.
Maybe useful for a 4x4 model

Instructions

Print :

4 wheels
2 frame
4 leaf suport
4 leaf
2 axle
2 "barre transversale"

1) Use acetone to glue leaf support, and frame
2) Use paper clip to get leaf on frame
3) glue axle to leaf
4) use some "nail" made from filament to clip wheels (heat the tip of the filament then flatent it on some metal)
5) use bicylce tube on wheel to get traction
6) do WTF you want with it
7) profit ;)

see it in action : http://www.youtube.com/watch?v=wenR0qu2uEY