Just finished the tumbler, and let me tell you that it is a paper folding nightmare. Almost as hard as the alien paperworks. I had to modify some of the fits due to vague instructions, but over all, it came out rather nice. I practiced on the wheels and they came out all right. I did not fold them as per instructions but rolled them to size and sanded the corners round. Because of this they are super heavy and I used a wooden dowel for the axle. Other than that the rest is all aper. Enjoy the model and good luck to all who attempt this build. And keep it away from the kiddies, they want to play with it.