The advantage of making a mold by brushing rubber onto the model is that it minimizes the amount of rubber used, saving you material costs. Making a brush-on mold, however, requires more time and labor vs. pouring rubber.  The following is a demonstration on how to make a mold of stone veneer using Rebound® 25 Platinum Mold Rubber and Foam-It® 5 Rigid Foam as a rigid lightweight foam backer.  Rebound® 25 is an incredibly strong flexible rubber.  Mixed 1A:1B by volume (no scale necessary), Rebound® 25 self thickens and will hold a vertical or inverted surface and will cure to a soft Shore 25A rubber. Foam-It® 5 Rigid Foam consists of two-component system that is versatile and easy to use. Foam-It® 5 will expand many times the original volume and develop a uniform cell structure.