Measure and cut the cardboard. You will need 2 pieces of cardboard that are 2 3/4-inches wide by 4-inches long, 2 pieces that are 2 3/4-inches by 8 1/2-inches wide and 2 pieces that are 4-inches by 8 1/2-inches.
Find the center of the 4-inch-wide by 8 1/2-inch cardboard pieces. Place your tube vertically on the center mark and trace around the tube. Trace one circle on each side of the center circle, evenly spaced.
Cut the circles out of the cardboard and cut the tube into three 4-inch sections.
Insert the tube into the holes of the cardboard, one at each end of the tube. Place glue around the tube area and the inside edges of the 8 1/2-inch pieces.
Create a rectangle by placing the other cardboard pieces around the edges and glue them down. Wrap rubber bands around the cardboard until the glue is completely dry.
Place glue over the sides, top and ends of the brick and cover the outside of the brick with fabric. Make four cuts in the inside of each hole to fold the fabric into the holes. Trim any excess fabric and glue the ends of the fabric down.