Another idea for those of you wanting to make troughs. Styrofoam boxes make a good easy square or retangular mold. These can be found in larger sizes from any pet or aquariam store as the aquarium fish are shipped to the store in them. They are usually thrown out and can be had free for the asking. Just find out when the fish shipments come in and be there to get the boxes before they smash them up. Carolyn