I have plans to make some simple ruins for the Frostgrave fantasy game setting, and for other 28mm gaming purposes. I will mix and match between bought stuff (mainly MDF) and scratchbuilt. For the latter I've decided to try XPS insulation foam board, so I ordered some sheets in 6mm and 10mm thicknesses to have a go with.
So far I've only managed a few minutes with this material - which involved snapping off a small piece from the 6mm sheet and etching some stonework on one side with a biro. This was much easier and quicker than I expected and I slapped on some undercoat and a couple of grey drybrushes to see what it would look like painted.
I'm happy enough with the results and look forward to trying some proper pieces, L-shapes, etc, with the 10mm material.
I don't have particularly grand architectural plans, I just want some wall ruins, with some window and door openings and a few partial upstairs floors to get a bit of height on the table. I think I need a quiet Sunday to really get going on this, but that may be a while away as things stand.
The ease with which this material can be carved has given me some other project ideas, so I may see if thinner sheets are available too.