First, draw two concentric circles, one big and the other small, so as to determine the thickness and size of the cylinder; Then use the REG region command to select two circles for the region, and then these two circles are faces. Then enter the SU difference set command -OK, first select the big circle -OK, and then select the small circle -OK, which is the bottom surface of the cylinder. Finally, enter the EXT stretching command -OK, select the object -OK, and enter the height -OK. That's all. This is a detailed procedure.