How To Make Flexible Foam Prop Cinder Blocks

Begin by placing the Mold Max 30 in its wood mold box. To help the mold maintain its shape, embed wood supports into the mold rubber. The lid should have holes which will allow the pressure of the expanding foam to escape. Apply Sonite Wax to both the lid and the holes in the lid to keep the expanding foam from sticking. Use ratcheting mold straps to firmly affix the lid.