1. Take two king sized rizla's (Blue/Silver).
2. With the glue at the top of the 1st rizla, cut a triangle off the right hand end, 1cm from the right at the bottom to the top right hand corner.
3. Attatch the bottom half of the 2nd rizla with the glue on the left hand side to the diagonal edge of the 1st rizla.
4. Cut the second rizla so the bottom edge of the 1st rizla continues along the entire length (Same shape from step 2).
5. Fold the L plate in half length ways, so the crease in the 1st rizla continues along the entire length.
6. Fold the top right hand corner of the 2nd rizla down to form a 45' triangle. Cut this triangle off.
7. Fill as you desire :)
Just the fact that I don't blame myself I'll wear a L-plate on my suit so the people know that I'm inexperienced.