The Waterfall fountain was designed with interchangeable parts that could be used to produce three fountains of varying heights.
When producing a multi-sectional sculpture, such as Roberts fountains, each tier needs to be consistent in shape, color, and texture. Projects like these make casting both a logical and practical choice. The primary advantage of casting was that it enabled Robert to interchange parts. Casting made every piece that came out of a mold an exact duplicate of the original. Fountains were originally thrown on the wheel. Before casting these fountains, Robert threw each piece and altered the form to produce every fountain. In the early 1980’s he was throwing 15 to 20 tons of clay a year. In addition to the fountains, Robert designed and made a variety of clocks and lamps using this technique. He also designed and made an aquarium using molds.
The entire pottery studio was redesigned to accommodate the molds, slip tanks, diaphragm pump, and tubing needed to move the slip from the tanks into the mold and later to suck the excess slip out of the molds and back into the slip tanks.
Robert is self-taught in the process of slip casting, which he pursued when a back injury prevented him from throwing for several years. The advantage of slip casting is the ability to make exact reproductions of a particular form.