UGEARS Wooden Puzzle, 3D Mechanical Craft Set, Christmas and Thanksgiving Gift, Engineering Adult Game, DIY Brain Teaser Due to the rubber engine this wooden puzzle can leisurely move on the rail track in both directions. You may connect a couple of rails with each other and set on movement a couple of trams No glue or any hand tools needed for model assembly - the parts are pre-cut by laser and you need jut to put them out Visual step-by-step instructions Great as individual or family project