Most of my buildings are painted with Humbrol enamels (over primer) and 95% of them are fine, but some of the roofs need patching up fairly regularly. I want to try re-painting these roofs with dark grey masonary paint, but having searched most of our local DIY outlets, they only seem to stock tins that are way too big (and expensive) for what I want. Does anyone know a DIY store that sells match pots of masonary paint?