I was lucky enough to find a role of wall paper in a charity shop (99p)which matches the PMC brickwork. I think they used this on the masters then cast in resin. It actually works well if primed with a grey.sand colour for the mortar and is then dry brushed with reds, browns, blues, blacks etc for the brickwork. Instead they have gone for the quicker option of washing the walls red, so all the pigment settles where the mortar would be, though to be fair the price is reasonable.