Abstract: An elongated flexible form is disclosed. The elongated flexible form may be shaped to fit the contour of a concrete structure of variable shape and is held in position by a plurality of positioning brackets. The flexible form is made out of a flexible material such as natural or synthetic rubber and may be reinforced by metal strips, cable mesh, metal mesh, nylon mesh or a combination of the same. Each of the positioning brackets has a hollow body portion which is molded to a flexible form or welded to a metal plate which is molded to the flexible form. A stake and wedge combination are used to hold each bracket in place. Connecting flanges may be used to attach the end of the flexible form to another flexible form or to a metal form. The connecting flanges are molded or welded to a metal plate which are molded to the end of each form and are held together by a fastening device. The flexible form has a plurality of ribs therealong said form to provide strength and to reduce the required thickness thereof.