Dima_y,
Thank you very much...

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Today's update...
I got the Plates soldered together in the oven last night before bed.
This afternoon I glued the templates on the 1/16" plate side and began drilling the screw holes for the Hard Drives to mount through. Here I'm just doing a small counter sink to give the bit a start point. (don't want it to walk)
After I got all of these drilled, I flipped the unit over and found center on these holes and milled out the recesses for the screws to 3/8" and milled out the crossover passage with 1/2" endmill so I can put the copper crossover tube in later.
Here I have test fitted the plates to some old (REALLY old) Hard Drives. Above is the existing drive cage. (left image)
The hashed area on the original cage is to be removed and the new plate/cage will go something like this... (right image)
Tomorrow I'll solder the crossover tube and double check the blocks for leaks.
One step closer... Peace!