I'm casting about for a way to construct a "skull" for a large egg shaped head and thinking that 1/4" foam would be too flimsy and 1/2" foam too heavy. Any thoughts?

Depending on how large the head i would difinetly suggest at least 1/2" heavy density or 1" regular density. Also it ill depend on what additional features you want to add on top ie cheecks, brow etc.

Julie

Also don't forget that you can always use "braces" inside of your foam head. It is one reason I like the L200 or EVA foam even when I am working with regular density foams. It can be used as braces on the inside. I agree with Julie that you need at least 1/2" foam most likely.  When you say "large" what do you mean? Mascot size like a person wears or somewhere between that and a "normal" hand in mouth puppet?

Sorry, but I should have written 1/2" instead of 1/4" and 1" instead of 1/2". The head will be just shy of mascot size. Any other ideas?