OK then this is your fall back method -- Prepare a Styrofoam cooler (cheap at Walmart) - fill with ice and your favorite beverage ( I prefer Canadian beer).
Step 2 is to spray the expandable 2 part foam all over the vertical surface to the depth and shape you want. Just go for it and make one hell of a mess.
After all the shaping and sanding is done to your liking (further adding to the mess) crack open the cooler and have a beer. Now wasn't that a lot more fun....