Over three years ago when I first got this project, building the doors was one task that could have been my first to do. Good thing I put it off, because it's best to have some familiarity with the tools and techniques to tackle this job.  :-)  It finally got started today. The top half of the door will be window, with a horizontal hinge in the middle so the window section folds out and down when opened. The first step was measuring and bissecting the vertical dimension of the door jamb, then transferring the vertical center onto the frames, cutting and trimming them.

The first photo shows the two halves of the left door (outside up) clamped to angles to keep the vertical sides of the halves straight, and measurement for the upper and lower center cross frames. It was important to make sure that the layout surface was perfectly flat, using the straight edge on the right. The bricks may have helped a bit, but just a few slight movements on the hangar's concrete floor was what quickly established the requisite über flatitude.

The second photo is a closeup of the horizontal cross beam gusset connections. The large blue clamp in the foreground has only a very light compression. Although the precise vertical separation between the halves will be established with placement of the hinge, I thought I'd put at least a piece of heavy paper between these beams for this stage of construction. Probably pointless but... it seemed like a good idea at the time.  :-)

The third photo (inside surface up) shows all the gussets drilled and clecoed, establishing the complete frame of the door. All that's left are hinges, skins, window, latch & lock, gap seals, air vents and.... In short, lots, but it's a good start, fun to do, and feels like progress.

The last photo shows the frame sitting in the left door jamb. On the inside, the gussets are riveted. There's no middle hinge yet, so the clamps are holding the top and bottom halves together, but the fit is great.