I tried to finish the block but both my cross vice and crappy piller drill have had it.
I think i could finish of the channles witht my dremel.
I was looking at a acrylic top mainly as i have a peice that would fit perfect.
I think the only problem with the copper sheet top would be any warping when soldering it to the base if it's too thin.
Is your 6600gt referance ? the xfx only has 4 holes 2 either side the gpu and 2 either side the agp/pci-e bridge chip. Not much to hold it at the top of the card.
I checked my collection of copper bits and i have a sheet of 1mm copper should be ok for the memory shim good idea