Oh yeah, I've already accumulated a few since I got the scratches out - a couple of ways to combat them 1) a quick pass with simichrome will leave a coating behind that inhibits some prints, or 2) paste wax!
But really I'll be re-buffing with the light grit scotch pad after assembly anyway.
And another tip I forgot to add before -- copper work-hardens as it gets hot, so you want to watch your cutting speed with the step bits and back off the RPMs as the bit gets bigger in diameter, else you will find the bit just... stops... cutting. It's not the bit, it's that the cutting edge is moving too fast and heating up the metal.
And use your step drills from the back of the plate as much as you can - the cuttings spin around and make nice patterns around the holes, but the scratches aren't consistent enough to be an attractive decorative technique!
...and another picture - the OEM bottlehead top plate with the 12x12 copper plate. I have to say again that the OEM plate is a very nice part, beefy and well-finished. I went ahead and drilled a hole for the volume pot I will be leaving out of the build for now (this will have 2 inputs with a rear switch and be driven from a preamp) - I plan to cover the center hole on top with the square Bottlehead logo plate, up front and proud.
Thanks for the comments guys!
/pRC
aka, Randy Carter - industrial designer gone bad in Raleigh NC