A park authority in south Germany commissioned the casting of concrete sculpture on its grounds. One example was a group of concrete trees which were made to conform with a natural background of fully grown trees. A common concrete base with protruding reinforcement was cast first. Each tree was then cast within a form made of thin sheets of plywood, bent to shape and rigidly clamped and braced. The fairy tale columns were made of conventional reinforced concrete cast in place. Foamed polystyrene blocks were glued to the form on the front side to obtain the various recesses. The form was stripped while the surface concrete was still plastic, so that the desired pattern could be hand carved. A set retarder was applied to the form to facilitate this work.