First up:
I made this last year for Rangers of Shadow Deep. It's double sided with grass/flock on the other side. Considering I've decided to continue playing Solo Frostgrave I thought I might upgrade the non-grass side. It originally had vinyl floor tiles that had a faux-stone finish and texture. It worked for what I wanted at the time but it needed a little bit of an upgrade.
The tiles had a self adhesive back but it wasn't holding well on the insulation foam core. So I pulled it of and glued it back on. I then gave the whole thing a couple of thick coates of grey coloured silicone caulk. After the caulk cured I used a sponge to apply some off white emulsion paint and then did a light dry brush.
It came out okay and it's very sturdy and the combination of sponge & dry brushing has given it an interesting texture. The insulation foam is 3' x 3' x 50mm. The edging is just gaffer tape (duct tape). All up it took about 1 hour (if you don't count the 1 day for waiting for the caulk to cure).