Is there a reason you don't want to use glass? I covered my cold frame with recycled windows from a salvage yard. Worked great. Lexan - the stuff they use to fabricate many greenhouses - would work well also but is pricey.

I have a double pane glass piece I would be willing to donate to your cause.

Thanks Flora: very kind of you.Indeed if we were closer I would take you up on your kind offer.I need lots of glass to cover though.
Thanks Gardengal: Glass is not out of question as yet.I think that the poly or fiberglass is lighter and cost effective.
Its going to be a big area so I want to keep most of the light without the UV.
Just need some ideas from my fellow gardeners.Thanks again.

I am using an old shower door. Yes it is glass, but it already has fittings for the hinges and a handle! Perfect! I founf mine at a place that recycles building material, so if you needed more than one, I would check at one of those in your area.