Having a flat layer of sand on the bottom of the tide pool seemed rather boring. Building a "beach" - rocky structure that would rise about the water level - would add some variety and make the tide pool more aesthetically pleasing to the children. It would also allow a place for the crabs to climb on. Keeping in mind that the downfalls of the last tide pool was using materials that were toxic, we were very careful about our design of the beach. We cut a piece of plexiglass to a 3' x 2' square. This would be the base, and would rest on the bottom of the tide pool. We cut 12 PVC pipes to lengths from two inches to ten inches. Measuring carefully, we cut out 12 holes in the base piece of plexiglass that were the exact diameter of the PVC pipe. We then stuck the pipes into the base. The PVC pipes were then standing straight up, and would serve as columns. We then searched for a type of mesh we could lay over the PVC pipes to create a mountainous shape that would be our beach. We found it in Rugstop, which is a rubber mesh whose actual purpose is to stop rugs from sliding on floors. We laid the Rugstop over the columns of PVC pipe, and poured concrete on top of it. Before it dried, we poured sand on top to give it a beach appearance. The entire structure weighted well over 50 pounds. There was some speculation that the plexiglass base might break in transport. We were relieved to safely deliver it to the tidepool. It sat firmly on the bottom of the pool, and formed a gentle hill that was partially above the surface of the water.