Select a cardboard construction footing form in the size you desire for the roller. A form that is about 3 feet tall with a 12-inch circumference works well for this project or you can use a 5-gallon bucket.
Cut a 2-inch diameter hole in center of the plywood with a handheld saw. Lay a garbage bag over the plywood and hole. Fit a metal pipe, cut to the height of the form with a pipe saw, into the hole so it stands upright. Cut the hole in the bottom of the bucket.
Set the form in an upright position so the metal pipe is in the center. Use a ruler to verify this is the exact center of the tube so the finished lawn roller moves properly. Set the bucket on a garbage bag and fit the pipe through the hole. Cover the top of the metal pipe with a piece of plastic to prevent cement from getting inside.
Mix quick-drying cement with water in a wheelbarrow. The amount needed depends on the size of cardboard tube used for the roller. A 5-gallon bucket takes about one bag of cement.
Hold the pipe sturdy in the center of the tube and scoop in cement up to the top of the metal pipe. You will need assistance with this step to prevent the metal pipe from moving. Let the cement dry and cure for a minimum of 24 hours.
Turn the cement tube onto its side and cut or tear off the cardboard form. You may be able to dump the cement form out of a 5-gallon bucket, otherwise cut it off with a handheld saw.
Cut two lengths of 1-inch diameter pipe about 4 inches longer than the tube. Fit the pipe through the tube and attach an elbow at each end. Fit a 3- to 4-foot length of pipe into each elbow.
Place an elbow at the end of each side length. Finish the handle by inserting the length of tube that matches the first tube into each elbow.