Being the cheep... err frugal person I am, I decided to use old pallets for the construction. It is sturdy but a bit heavy to be used as a tractor. (Wife has a bad back) I have not even added the run part to it yet. Thankfully I used Sheetrock screws to put it all together so dis-assembly and redesign won't be all that hard. If at first you don't succeed, read the directions.