I sometimes take on some "odd" jobs, both for the challenge, and the getting paid part. This one involves a material I was only vaguely aware of, plastic millwork. I've seen the plastic frames for years, thank goodness for odd painting sizes, but don't spend enough time in the regular lumber store. Recently I was asked to make an arched element for some ornamental work for a porch, and was supplied with the material; two 18 foot by 11 1/4 inch boards made of plastic, polyurethane.
Above, one of the 18 footers, halved and now being laminated into a 9 foot by 22 1/2 inch board from which to cut the arch from. Gorilla glue, after some research seemed a good choice, the deciding factor being reasonable availability. The glue joints only need to last til the arches are installed; then contractors adhesive and mechanical fasteners will hold it in place. I did try and snap my test piece; two little cutoffs glued together, by pressing down, hard, on the supported and unsupported pieces. Still together.
This image shows the layout on the boards. I did the layout prior to glue-up, so I would know where the critical areas were for clamping. The arch was drawn from a 1" x 10' x 1/8" piece of plywood, that I cobbled together from 2 5' strips of the plywood held together with a small third strip, about 3 inches long, super-glued to the back of the longer strips. 5 minutes, done. Capturing the 10' strip at the center, between 2 thin, clamped pieces of scrap, I could bend the strip, clamp it at the end, and draw the arc out to the center, then do the other side.
More, later, as it progresses.