right. Eight 1.5 x 2 x 0.5" does seem like a more sensible option (and a better way to end up with a couple to sell, maybe one for pH to test etc)
As for methods at our disposal: My friend is an acrylic god

and pretty much anything that can be laser cut is possible for top plates, within some reason, of course. We're looking at getting the bases professionally CNCed, so again, pretty much anything is possible within reason. Would rather not go super-complex and attempt to make a Cascade SS ripoff, due to the extreme # of prototypes and testing required to get the desired result (unless Cathar wants to make a friend for life and share his specifications

) but again, most designs are possible - was just wondering if anyone had a special "silver optimized" design or something of the like - Ben's Radius block is interesting, but it seems that someone else is working on that, and it would require seriously hardcore machining and lots of silver.
EDIT: Just had a thought - 1.5"x2"x0.5" = 38.1x50.8x12.7mm take a mm off each edge, for cutting waste, and you're looking at 36x48x11mm or so. That means that it will cover a full P4 IHS (31x31mm) but there will be a mm of exposed edge on each side of an Athlon 64 IHS (38x38mm)
Is this mm of exposed edge a concern? I'm not worried about crushing the core due to the IHS, and I believe that the heat shouldnt spread all that much to the very edge of the IHS if its being cooled in the center over the die, but I thought it was worth bringing up.