Our parent testers were wildly enthusiastic in their praise for this Marblecity construction set. They called it a work of art. It’s true, right out of the box this product oozes quality and craftsmanship. The laser precut wood pieces are sturdy and durable. The directions are clear and concise with plenty of fine details about how to put all the parts together. The book tells a story using graphic illustrations to teach lessons about engineering and physics principles. This is definitely not for younger kids, nor is it a quick and easy thing to put together. This will take hours and hours of concentration, precise fitting and gluing. Our testers averaged roughly 6-7 hours from start to finish. When you are done, besides having a beautiful wooden replica roller coaster that actually works, your child will have learned valuable lessons about kinetic and potential energy. It is not possible to take the Coaster apart and reassemble but that did not detract from the rave reviews even a little. Fully assembled it amazes everyone who sees and plays with it.