The first time I used PVC-Foam board seriously was on the quayside wall built for Furness Quay. At the time I was mightily impressed with the way it cut and scribed.
Moving to the Selly Oak canal, I need to represent some concrete lumps in the banks around the bridges, so decided to give it another try.
My method involved scribing the joins then glueing into place the vertical part with PVA. Once dry, I thought I'd trim it to perfect height with a knife, but after a flash of inspiration, pulled out a small plane that is older than I am.
Despite the unsophisticated razor blade, it worked breathtakingly well. Gently stroking the plane along the edge of the 2mm thick board produced a neat curl of material. I've never been able to do that on proper wood, so the results here were amazing. This is certainly something I'll remember for the future.