I designed and built this recently. It's 9 and 1/8 inches long, 3.5 inches wide, and 3.25 inches high. The components are two layers thick. There is a 110 lb. cardstock structure layer, overlaid with a white construction paper layer, on which I printed the pictorial details, then colored with crayons. The wheels roll. Each wheel is made from two corrugated cardboard discs, covered with cardstock. The axles are segments of 1/8th inch diameter skewer sticks. Design method was old school; ruler, pen, circle and curve gauges.