Once you have all of the cameras placed and spaced properly trace the camera positions w/ a magic marker directly onto the ply wood. At this point you have all the necessary guidelines drawn that you need to cut the wood. Use the jig saw to cut out the arc. Make the width of the arc deep enough to comfortably mount all of your cameras and equipment. You may need to use two pieces of plywood to create your full arc. You can connect two pieces together by "sandwiching" the two (or three if its big enough) section of the arc between two pieces of plywood and securing them with large industrial clamps. Ours was roughly 9" deep. Be careful not so set the cameras so far back that the edge of the wood shows up in the bottom of the frame.