Measure and mark the cardboard tubes to the proper length for the pillars you want to build. Set the fence on your table saw so that the fence is equal distance from the blade to the piece you are cutting from your tube. Set the blade as high as possible.
Start the saw and carefully roll the cardboard tube through the blade, turning the tube back toward you until the tube is cut through. Turn the saw off and allow the blade to stop before retrieving your pieces.
Use the off-cut piece as a template and set it on a sheet of 3/4-inch MDF. Draw two circles for each pillar. Cut the circles from the MDF using a band saw.
Use your table saw to cut one square 3 inches wider than your circles for each circle. Apply wood glue to one face of each circle. Position each one on a square, centered in its face. Use 1 1/2 -inch nails in a pin nail gun to nail the circle onto the square, one nail every 3 inches.
Fit one of these caps into each end of each cardboard form, so that the circle fits inside it, and staple through the cardboard into the edge of the circle, one staple every 2 inches.
Cut 3-inch-wide strips of hardboard 1/4 inch thick, enough to wrap one around the top and bottom of each corner and to run one vertically up the face of each pillar, every 3 inches.
Wrap one strip around the top and bottom of each pillar. Cut the strips to length, using a miter saw, so that they fit neatly around the pillar. Staple them in place with 1-inch-wide crown staples from an air stapler, one every 2 inches.
Fit one strip vertically between the top and bottom strips you stapled around the pillar every 3 inches. Staple the vertical strips in place with one staple every 4 inches.
Tear muslin into 6-inch-wide strips. Mix latex paint one part white glue to two parts paint. Brush the mixture onto each pillar with a disposable brush and paste the muslin strips on top of the paint. Paint over the muslin to smooth it. Cover the entire face of each pillar from top to bottom and allow it to dry for 24 hours before using the pillar.