Things You'll Need
Instructions
Measure a 12 1/2-inch by 25-inch rectangle on the poster board. Find the midpoint on the long side of the rectangle, at 12 1/2 inches, and make a straight line in the center, leaving you with two squares.
Extend the top and bottom of one of the squares by 1 inch. These will be the tabs that hold the cover together.
Cut around the outer lines of the rectangle, including the tabs, using a craft knife and metal ruler so the lines are perfectly straight. Do not cut the center line.
Fold the tabs so that they turn inward. Slide a bone folder or the back of a scissors blade over the fold to make it sharp.
Fold the rectangle into a square along the center line so the tabs are on the inside.
Open the cover and apply a small amount of glue to the tabs. Do not get glue anywhere else on the cardboard, or you won't be able to slide a record into the cover. Fold the front so that it meets the tabs and press it down.
Allow the glue to dry completely before putting a record in the cover.