Just finished the marble run, works just fine, enjoyed the challenge. I would suggest using a lite silicone grease as I think it works better then the wax. I build RC cars and trucks (have 27 of them) most kits come with some of it I used it sparingly it helps everything work better. Now onto the airship, got two at the same time would recommend to any one who enjoys a challenge will defanatly be buying more of them. Thanks