The present invention provides an apparatus and method for fabricating structural building panels. The apparatus may be used for fabricating panels directly on the foundation for a building. The apparatus may include a support frame, a flattening frame, a press frame, drive members such as pneumatic cylinders supported by the press frame, and posts attached to the support frame and used for aligning and coupling the apparatus and panel components. In order to fabricate a structural panel using the inventive apparatus, drywall sheets having bores sized for receiving the posts therethrough are prepared and drywall ribs or spacers are cut from drywall sheets. The support frame may be located on the foundation where the structural panel is to be positioned and a first sheet and a second sheet placed onto the posts, the sheets having adhesive and drywall spacers positioned perpendicularly therebetween. The flattening frame and the press frame may then be placed onto the posts and the press frame locked on the post to prepare for compression of the panel components. Upon actuating the pneumatic cylinders, cylinder rods press the flattening frame members against the second sheet, thereby compressing the panel components against the support frame. After the adhesive which glues the sheets and spacers together is sufficiently set up, the press components may be removed from the fabricated panel.