t was simple really, just headed over to Home Depot and purchased 18 clay bricks, the ones that are half the width of regular red clay bricks. When we returned home we then lined the sides and bottom of our BBQ grill and voila! Instant brick oven. It cost about .17 cents a brick, too. Nothing to it. If you have a tile saw you could also make the 2 side ones that ended where the lid closed cut on the diagonal to seal the deal nicely.