Smithsonian

Are your kids ready for a challenge beyond snapping together a see-through model of the human body? Here you go! Let them immerse themselves in a world of adventure and discovery as they build a real battery-powered 4-cylinder model engine, piece by piece. When they are done, they'll have a model adorned with moving parts, lights and realistic engine sounds. Valves open and close, spark plugs fire and pistons drive the crankshaft, just like a real internal combustion engine. Built product dimensions: 8.5in.H x 8in.L x 4.5in.D.