I've built a circular fire pit using cinder blocks 6x8x16 and then mortaring manufactured stone veneer to the outside. Since it is such a small circle this was not an easy task, but I did finish. My question now is on putting the top cap on to finsh it off. the top cap is straight and measures 37" x 12". I'm going to have to cut it into smaller pieces and then arrange it into a circle. Is there a way to figure out how small to cut the pieces needed based on the diameter/circumference of the circle or any other way to make this easier.