Are their any inexpensive and more importantly safe alternatives to the silicon ge offers?
+1. I use gorilla glue for all of my backgrounds, usually with carved and heat gunned polystyrene sheet and ground xaxim. Gives a gorgeous natural look, with minimal effort. Here's my most recent effort so you can see for yourself how well it works:-if you are just looking to glue stuff to the background, just use gorrilla glue, dries fast and expands.