Your correct, they are using Great Stuff foam. Cost about $4-5 per can, depending on what size can you get. I personally don't know of any websites or book that specifically details the use of Great Stuff, but here's an address you can start with. Haunted Attraction Magazine Online Check the lower right side for a few things you can do with Great Stuff. You can also type the word into a search engine, Youtube, or other places to find some ideas. You can lay down some wax paper and spread something like Vaseline or something along that line so that it doesn't adhere to it when it dries, and just spray squiggly lines on it, or something resembling guts. Just get your hands dirty and experiment, you might be surprised by an accident that turns out great. Good luck!!