Hi all..I've been playing around with some lightweight mixes also..I"m ordering some very small eps beads right now..I've worked with the perlite and still am experimenting..however, perlite tends to soak up water..and so, your mix needs water added quite a bit and often..also, I'm trying to find a way to make it much stickier..don't know exactly what to add yet. I found some shower floor mix at home depo that is a lightweight mix..however, I can only build it out about two inches before it tries to fall off the wall..however, it stamps very very well..and get's very hard. I'm also adding polymer to it. If anyone knows of something to add to these mixes to make them stickier..I'd like to know also. Here's a pic of the latest things i'm doing..