A method and apparatus for assembling components of a workpiece. Some embodiments include a work surface; a first digital projector that projects an image of at least some features of the workpiece onto the work surface, wherein the image includes a plurality of line indicators that have visually discernible different markings such as colors or line types; a camera that obtains input images of the work surface and the components of the workpiece; and a first controller configured to receive the input images from the camera and to control the first digital projector to project the first output digital image on the work surface for assembly of the components to form the workpiece, wherein the first controller is further configured to store distortion-correction parameters and to use the stored distortion-correction parameters to adjust the first projected output digital image. In some embodiments, the workpiece is a lumber truss.