[Del]

I just recently received my Maze 3, and to my dismay, it had the countersunk bolts, and it resulted in cracking.
I have decided to make a new top for the Maze 3 out of copper and I have attached the blueprints below.
I am wondering if anyone could check these figures and maybe fix them.
I also need to know what size tap I would need to use the 1/4 npt 1/2 inch barbs?
I assume I have to drill 7/16 " holes.
Would anyone know whether it would be possible to get thick copper sheets, (thick enough for the top) at the local hardware store? I live in Canada.

I also had to lap the block, as it was very concave in the center.

However, I am still satisifed with the block, as it has been machined very well, and

Thanks for your help.

Edit: I fixed the image, so this should correspond to the actual..
I can't believe I missed that.