By hand. I used a small fine-toothed Japanese saw. The most important thing is that the PVC plastic has adequate support next to the saw cut. (I placed several boards on the trestles.) After some practice, it went really well.
Absolutely angle grinder and cutting disc! It's quick and there's little risk of cracks. There's a bit of melted plastic on the edge but it usually can be easily picked off with your fingers.