Hi, a question when trying to figure out a solid with holes inside. For example, the "meshgrid" creates a 5*5 matrix, but I only need to use the central ring area to create solid ring-cylinder. I tried to set the thickness of those pixels(unwanted) to 0, but it still carried out a flat plan covering the whole 5*5 area (I expect no solid in the center hole). How could I set it? Thanks so much.