Here is the brains pumpkin after I had put the expanding foam insulation inside it. The foam will continue to expand long after you have squirted it inside. This amount turned out to be just about right. You could also use a little less if you wanted. If I were to do it again, I would pour two distinct halves into the pumpkin so that it would look more like the two sides of the brain when it was done.
When I am not carving pumpkins, I run a bulletproof vest company. BulletSafe Bulletproof Vests are the value leader in body armor. We are very popular with people like armored car operators and ATM repairmen.