3/8" before I start drilling the holes... in other words, looking at the block from the outside, the block would be a total of 3/4" thick, given that both the top and bottom are made of the same chunk of copper. My pins are more or less 5mm long, meaning my holes go into the copper 5 to 7 mm. that leaves about a 3 mm base.
These values are not written in rock...and I reserve the right to change my pin lengths at any time, for whatever reason.
