Heres a page to look inot and consider.
http://www.garbled.net/tim/fiberglass.html
It basicly tells you how to work with fiberglass without a mold.
I would almost want to make my own custon box cover. It'll save you a mint, and it'll have the features that you want. You can make it fold in the middle if you want or just about anything.
Other than that a google search seems to have several.
If a google search doesn't give you what you want try the other search engines (msn, yahoo, dogpile ect) I've noticed that Google doesn't show everything