for this you will need: electrical tape (any tape should do) cardboard hot glue clear plastic CD case something to cut the plastic with
Step 2: The plastic
cut a rectangle out of the plastic trying not to crack it. the width should be the diagonal of a square on the board and the height can be whatever you want.
Step 3: The base
Cut a square out of the cardboard the same size as the squares on the board. Apply the tape to the top of the cardboard square for thickness and strength. put a bead of hot glue across the diagonal of the square and stick the plastic in it, keeping it upright.
Step 4: Finish
Before the glue completely dries put the piece on the board and fire the laser to make sure the shot lines up.