So here i am being a cheap skate and instead of purchasing a $350 4x5 reducing back for my 8x10 tachihara, i decide to build one. Why? cause it will cost me only $50 the most and it will work perfectly fine and be even lighter than the $350 one.
I may have to agree that the factory version will look heck of a lot better but if you are somewhat skilled , you can make yours look decent too.

So headed out to Home depot and got myself some big sheets of 1/4" plywood.. I picked the flattest piece.. Got it cut to 11 7/8" square pieces there, which took the guy 2 seconds.

Came home and picked the flattest piece and threw it on the camera.. Fits nice.. No warping

Now, off to build the light traps and to cut out the hole to accept the 4x5 graflex spring back which is mounted on a 6'x6' 1/4 board(needed for the clearance of the Polaroid 545 holder.) And i also use this 4x5 back on my 4x5 ikeda anba woodview camera.

so i bring out the dremel tool and cut out the 6x6 window out the back. then i cut 4 strips of 1/2" wide 1/4" wood to be glued to the back to act as light traps that go in the camera.

then all the edges are sanded and smoothened.
I then put the 4x5 back on the 6x6 window and mark the edges to drill for the bolts.

I drill the holes and screw the nuts and bolts. I realized that since the wing nuts I used donít have much surface area to hold the 4x5 back down i had to put small pieces of woods on the other side of the bolts to keep them from flexing too much. I used plastic bolts, they are light but they flex so the wood stiffeners were necessary.

Additional material removal from the board was necessary for the Polaroid back clearance and it took 2 min with the dremel tool and a round sanding bit.

When all the assembly was done, i stained the wood with minwax mahogany stain.. The plywood doesnít take the staining very evenly, so you may want to use some other brand of stain and polyurethane. It looks fine too me but if you want a gorgeous looking back you should try some other brand.
I painted the inside of the back flat black to eliminate reflections.
Viola, my homebrew 8x10 to 4x5 reducing back was born in just 2 days. It was a lot of fun to build it.

Now on to the next project, building a 7x17 back for the tachihara...