I have had a pack of laser cut ruins kicking around for a while and never used them.
They were designed for use with sci-fi games (40K presumably) but I have re-tasked them for Frostgrave.
I added a base to most of them (the bases were unused from skirmisher trays and were just the right size for the task) then PVA glued them, left them overnight and painted them.
Painting was a basecoat of cheap grey emulsion followed by a drybrush of an off-white. Very straightforward but keeping the paint light enough to keep the detail on the walls of the ruins (the laser etchting is not very deep).
Some of the ruins had an extra higher shooting step added in the corner to help archers and the like in the game (!)