So, I picked up my custom playmat today... It's 1.2m x 2.0m made of PVC with a nice starfield on it. Wasn't too expensive either: R270 (which is around $25).
Problem is: Folding the mat creases it badly, especially around the corners where multiple folds come together. This means using it like a tablecloth will probably ruin it pretty quick.
My conclusion is that the material was probably not suitable so it's back to the drawing board. The PVC is quite thick with a kind of mesh pattern on the back of it.
Anyone else made a custom mats that doesn't suffer this drawback? Any suggestion of alternative materials?