1. Measure in from the short side 15 inches (1/2 the width) in several spots making guide marks with a craft knife. Then using a metal ruler cut 2/3 of the way through the board. Do not cut through the whole thing.
2. Gently fold the board toward the uncut side, creasing the backing paper.
7. Add a strip of Duck Tape to the uncut side of the triangle to strengthen the fold
More about this project in an upcoming post.