A simple technique for site-casting of designs has been utilized on the balconies on Chicago's lakefront. Standard plywood panels are used for the first layer of the forms. The second layer, of three-fourths of inch thick smooth plywood, is cut to the pattern for the design and nailed on the first layer. The third layer, of five-sixteenths inch thick striated plywood, is cut to pattern and nailed to the second layer. This results in a patterned form of 3 planes. All edges of the nailed on pieces must be bevelved to facilitate stripping of forms. A retardant is applied to the lowest form. After the forms are stripped the areas which were treated with the retardant are spayed with water and brushed to expose the aggregate.