Abstract: A form into which concrete is to be poured has rectangular rests on its bottom for placing thereon the outer frame of a sash window or the like. The outer sash frame is secured to the rests by means of several spaced-apart fixtures arranged on the inside of the rests. Concrete is then poured into the form, and upon its solidification, the precast concrete panel is withdrawn from the form with the built-in outer sash frame. Each fixture comprises upper and lower holders that can be actuated manually into and out of engagement with the upper and lower flanges, respectively, of the outer sash frame on the rests.