There is a rectangle between the upper and lower circles of the same size, and the "length" of the rectangle is slightly larger than the circumference of the circle. The key is how to paste. A circle and a rectangle can be pasted together. Personally, I suggest that a rectangular paper roll be directly made into a cylinder, then cut vertically at both ends of the cylinder at a certain distance to form a plurality of small faces that can be folded inward, and then stick a piece of paper at one end of the cylinder at will, and cut a circle directly according to the shape of the cylinder, so that the circle does not need to be made or calculated. If it's for painting, it's big. Ready-made tissue tubes can be made directly.