Blackmagiccraft on YouTube does a ton of tabletop game terrain, buildings etc. I mention it because he has the foam and painting completely dialed in. Where to get the cheapest stuff, what sprays wont melt the foam, how to protect it etc. ie dollar store foam core, tear one layer of the paper off, draw bricks with a pencil into the foam, texture with a ball of tinfoil and paint. Comes out looking like real stone.