All you need is plastic and a heat bender. Luckily, i have access to a heat bender at TechShop in San Jose, CA.
As a note, you should always do a test to make sure that your plastic can be heated and formed. Some plastics like poly carbonate with show black specs when heated, and these will not go away. In addition, I do not recommend heat bending material more than 3/8s of an inch thick.
Anyway, you have to bend plastic, and you want to do it right, so this is the place for you! Now, onward, to the instruction!
Step 1: Prep! Removing Protective Film and Marking the Plastic for Meassurment
The easiest way to mark your plastic is to use a sharp knife. Carefully mark the areas you want to bend with a light scratch. This scratch can be buffed out, or will normally just melt back into the plastic during the heat bending process.
Step 2: I AM BENDER, PLEASE INSERT GIRDER!
You can test your plastic to see if it is malleable. Once it is easy to bend, you have found the right spot. Take it off of the bender and put it into an adjustable angle setter or a pre made mold with the appropriate angle cut into it. For the best results, push your piece into the setter and then clamp it down. You should only have to wait a few minutes until your piece is cool enough to handle!
As a finishing note, you may have noticed that the outside edges ave bowed a bit. feel free to sand them down, they are essentially jump left over squished material.