I found my foam on eBay. There are quite a few sellers that offer the Density 1.7 Polyethylene Foam Sheets in different colors and densities (higher density = "harder"). I bought my foam from Hexapackaging. They offer 2 ft X 2 ft and 2 ft X 4 ft sheets in a variety of thicknesses ranging from 1/2" to 2".
This foam is not cheap ! A couple years ago I had to send my 180 EDT back to Astro-Physics for some upgrades. Since I did not have the original shipping carton, I had to make one using these 2-inch thick foam sheets. At the same time, I also had to replace the foam in the wood storage case that came with the scope. This project cost several hundred dollars. The moral of this story is to save those shipping cartons with all of that high density foam.
