Some one in a "backdrop" thread raised the topic of backdrop support and styrene was raised as a possibility. I have a friend who just installed 55 feet of it on his layout (but double sided so over 110 feet of it really). The first issue was seams. He experimented and went with an auto bondo epoxy that is easily sandable; he felt it would hold up to the flexing better than anything else he had thought to use. It worked well. Seams weren't invisible but almost. He laminated two .60 mil styrene 4 by 8 sheets together. The entire 55 feet is curved one way or another which added to the stability of the sheet styrene when it was standing up. The top of his backdrop is only about 4 inches from the top of his ceiling. For support he sort of designed his own "clamps". He basically used wood supports that were roughly 1 by 1's, that he cut length wise down the middle and slid the two laminated sheets of styrene into it. The supports went up about 16 inches. These supports will be hidden as mountainous area will be located where they are. The cost in Canada for a 4 by 8 sheet of styrene is about $23 so cheaper in the States most likely. He then at either end of the long sheets (joined together), flared the two sheets out (at each end), with a piece of wood about a 1/4 inch wide going the length of the end painted white to give the ends a finished look. It is very effective. He then painted three colours of blue on the sheets and blended them together for his sky. Since his background addition, his layout looks about twice the size it originally did. You can't see the entire layout now, and the backdrop breaks the layout down into areas, rather than one large composite. So with "separate" areas, the walking and visual "take in" seems much vaster.