I under-estimated the space I wanted and would like to expand the fascia edge of my shelf-layout about 3-4". I am thinking of using 1" thick construction foam board - ripping it in 4" x 8' lengths and then laying a piece on top of that such that it'll be flush with existing fascia and layout surface. I'd spackle and fill in the seam and paint. There is a gentle radius involved, thus I need to be able to bend whatever material I use. This extension is only for foreground scenery and will not support tracks or anything that heavy. I am thinking liquid nails will hold the pieces to existing fascia and each other. I cannot think of any other way to expand?