Glue five pieces of cork to a piece of 1/4-inch-thick glass to create the bottom of your record-flattener. Place one piece of cork in the center and the other four pieces of cork in the corners. All the cork must be even and level. Set aside a second piece of glass for the top of the device.
Trace out the shape of the record on two vinyl-foam placemats. Cut two record shapes out of the placemats. Cut center holes out to leave the label exposed.
Clean the record with glass cleaner and a soft cloth. Wipe in the same directions as the grooves on the record. Rinse with distilled water. Dry the record with a lint-free cloth.
Place the record between the two pieces of glass, with the vinyl placemats between the record and the glass on either side.
Place the record sandwich outside in the sunlight for 15 minutes. Move the record sandwich back indoors. Set it in a stable spot and place a 12-inch marble tile on top. Leave the tile on top overnight. An alternative to the sunlight method is to set your oven at its lowest setting, 150 to 200 degrees, and place the record sandwich in the oven for 15 minutes. Turn the oven off after 15 minutes. Leave the sandwich in the oven and place the marble tile on top. Leave it overnight.