the method of the invention includes the steps of positioning a support member having a substantially vertically extending recording surface thereon in the doorway for which the door is being sized , recording the contour of each side door jamb of the doorway on the recording surface by transposing the contour with a tracer mechanism having a follower adapted to be advanced along each side door jamb and a marker for recording on the surface information corresponding to the contour of the side door jamb , placing the recorded information in a cutting apparatus having means for controlling a cutter device in correspondence with the recorded information so that the cutter device is advanced along each side of the door member to cut the sides of the door to match the contours of the associated side door jambs . the apparatus of the invention consists of a vertically extending support member having a sheet of material extended vertically therealong , a centering assembly for positioning the support along the central vertical axis of the door opening , and a tracer mechanism movable along the support member and having followers adapted to engage the side door jambs whereby markers on the tracer mechanism will mark lines on the sheet of material as the tracer mechanism is advanced along the support member with the lines corresponding in contour to that of the associated side door jamb . the support member also includes adjustable means for comparing the head door jamb with horizontal .