I've been using PVC sheets for quite a few of my projects and decided it's better to just write one article I can link to rather than rewriting this every time.

Anyway, this is a super useful material that can be located for very cheap or even free. I get mine from a local recycling centre. It comes in various thicknesses, but I really like the 5-6mm thick PVC

Supplies

PVC
Oven, Gas cooker or other heat source
Flat boards
Something heavy

Step 1: Cut the PVC Pipe

The first step is to cut your PVC pipe into sections that can fit inside your mini oven. If you want to make bigger sheets you will need to use a larger oven or other heat source.

You can cut PVC using nearly any saw, such as a handsaw or circular saw.

Step 2: Flatten the PVC Into Sheets

Turn on your mini-oven or camp stove and carefully heat the section of PVC pipe. You must keep an eye on the PVC during this process so you don't burn it! Also this should be done in a well-ventilated area as plastic fumes are probably harmful.

Once the PVC pipe has become soft place it between two flat surfaces and put something heavy on top or stand on it. Wait for the PVC to cool down and you will have a nice PVC sheet.