Do we even do terrain here? Well I put some minis on it so I am pretty sure this still counts. ;) I finally finished a large chunk of the terrain I had begun a few months ago so I put it on the table to see some possible layouts.
All terrain is crafted from scratch from XPS foam, sand, toothpicks, some bits, tufts and moss. Heavily inspired by Black Magic Craft on YouTube (namely modular ruins, dungeon tiles, pillars, dungeon stackers). The acid pools and spike traps I came up with myself.
I've always been a little leery of xps foam. Looking at your stone ruins makes me want to give it a go.