Reply to "How many here scratch build using foam core board ? What paint is best to use on foam core board?"

I love working with Foam Core and agree it does tend to warp when painted.  Here are two Foam Core buildings I completed this year and placed on the TMB club layout. The brick face building had wood slats and some wood strips behind to minimize the warp. The steel mill was used to show trains coming in/out of the factory rather than a another portal. There I glued 1x2" strips of manila folder that were crimped to look like corrugated metal. Then it was painted and weathered, NO warping here.