Just in case anyone doubts the power of craft foam board, the Mega Cereal Bowl shown in the video in my previous post is mostly made from the 1/2" stuff. I hear the one in the video has a 75mm mount and the owner has a 98mm version that flew at the same launch. For those who want one, here are the plans. Well, that one is only a 54mm version. OK, OK, OK, there is some fiberglass involved. On the bigger ones some carbon fiber. Still, not bad for mostly styrofoam.
The biggest foam saucer I have is the Art Applewhite's 18" Delta, which is made from a dense foam board called Gatorboard. It flew mine twice on a 38mm J228 and a 54mm J110. Others have flown them on K's, so it is pretty sturdy itself.