A casting tool for forming precast concrete wall sections. A base is disposed generally in a horizontal plane and has an upper surface. A pair of opposing sidewalls are disposed proximate the upper surface. Each of the sidewalls has a first position in which the sidewall is located substantially in a vertical plane. First and second opposing bulkheads are disposed proximate the upper surface, each having a respective first position in which the bulkhead is located substantially in a vertical plane. The bulkheads are arranged to abut the pair of opposing sidewalls so that the inner surfaces of the sidewalls, the bulkheads, and the upper surface of the base define a form for receiving concrete to make the precast concrete wall section. The first bulkhead is configured for movement so as to vary a first dimension of the form, and thus the dimension of the concrete wall section.