Good Morning Steve.......I have only used the cookie cutter plywood type of construction. To cut the curved pcs. I would make a large compass out of tempered Masonite wide enough to mount a router with a spiral straight bit, on one end. then make holes for a bolt pivot point at the desired radius. The 4x8 plywood was laid down on the shop floor on top of 4x8 extruded foam(not white bead board) another sheet was laid down at right angles making a T for the pivot point. I made 120" dia. curves. I cut more than I needed but I wanted plenty, so I would not have to do this again. I sold my extra's on this forum. The waste pcs from cutting out curves from a rectangle where used for flat scenery base or mountain forms. The router cuts cleaner and smoother, the curved pcs also make a good jig for bending Gargraves track. Next time my curves will be larger. With plywood laid flat on styrofoam the router cuts right through it, the router bit only sticks out of the plywood a fraction of a inch. also you don't have to worry about the cut off piece falling or binding, you also don't have to layout your curves, I cut my curves out of the long side of the plywood. I make all my plywood cuts laid on top of styrofoam even with the Skill saw. the styrofoam is then used for scenery. A one armed person can make these cuts by himself.
Clem
