CONCRETE COUNTERTOP EDGE FORM CEF 7007 Concrete Stone Venner Mold Globmarble supplies professional grade casting molds which reproduce the structure and relief of natural stone to the smallest details. Molds made of two-component polyurethane or silicone rubber proved their high quality and durability. GlobMarble molds are designed to produce many parts and will last you many years by using a little common sense and incorporating a maintenance plan. HOW TO MAKE CONCRETE STONE: Apply release (can be used liquid soap). Mix concrete per instruction, add colors, vibrate the mold lightly to remove an air bubbles, remove the stone in 24 hours.