I admit, I borrowed most of this idea from a fellow crafter, A great use for scraps and those little wheels I couldn't think of a use for.
3/4" poplar, 3/4" wheels, 7/32" axle pins and 1/4" dowels
Each vehicle is about 3" long. I have to admit, I did make a couple cuts on something other than a scroll saw, but axles, turrets and jeep passenger area were done on my EX21.