The wood for the extension back was Limbala and was a dense textured hardwood of open grain. It was what I found laying around in the shop, it was so hard that I had to use a wood lubrication when I ran it though the planer. The joins are box and very tight, I used guerrilla glue and it was had to sand but turned out extremely strong. The hobby shop provided some brass that the I cut with a hacksaw, drilled and filed then buffed on a huge buffer I have. It's easy to make one but to make a duplicate but in the reverse is more challenging by hand. I pared them up and sized them on a Delta 12 disk wheel holding them in vise grips with cloth to prevent the brass from getting scratched. I made it in three days before leaving for a workshop and everything was done quickly without undue delay. I used tung oil for the finish and it was still smelling from the second coat when I got to the hotel in Tonopah.
I was looking at the camera design and stretched the bellows way out to see what the maximum usable extension was and found that it was a lot longer than the 12 inches of the camera design with its single extension. I looked for a way to design and replace the rails in the back but when I removed the screws I found that the entire assembly could be moved. I moved it back and exposed two screw holes. That was 2 inches and it was very stable. I decided to make a wood block of light weight gum wood to fill the space and add support and it worked better than I originally thought. All of the screws were put back in so there are no extra parts to get lost. I had to route a stop dado into each side for the metal locks on the inside to slide in. It's just like the dado in the camera base as seen with the two blank screw holes. All in all this can be done without the block in a couple of minutes with a small screwdriver. Add the block and get better support.
I'm not fond of the camera because the knobs are too small and it's difficult for me in the cold but it's an OK beginner camera. A 5x7 would with larger knobs would be better and a double extension. I like the knobs on the Chamonix and the hardware is much nicer but that's a different story.
What I've learned by this inspection can be applied to a camera I have wanted to build for some time. I have the parts, including a Canham 5x7 bellows with the metal end plates. I built my first 4x5 field camera out of Cherry and brass by hand and small machinery over thirty years ago. It's a lot like the Shen Hao and has the same problem for me, small knobs and short bellows. I think I've learned enough to make my perfect camera or cameras. The last comment I have about the Shen Hao is the color of the wood, it looks like a sick or bad stain job. I just don't like the color or the choice of wood, it doesn't have any bearing on the function but is an aesthetic issue as is the black painted brass, I bet the brass would be beautiful if stripped and polished. I have gone as far with this camera as I want to go and for what it is it's worth the money. Add an extension back and extend the rails and you get a sturdy 16 inch 4x5 which isn't bad. And the camera actually has the ability to move the rear back and the lens standard forward and add even more extension however this set of movements puts the locks to the extreme and a heavy lens will sag and not be stable and prevent small movements and adjustments.
Thanks for letting me share this with you,
Curt