The problem will be dremel it to the depth of say 8 mm. At least with emery discs I have.
That's what I thought, 1.5 - 2 mm in the drill pits. A 'varialble base thickness'
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NP for copper, if u change your mind, half of that slab is free for ya!
I can try to make the flat top on bottom half, but the base is still thick, and the passages cutted to half. Think I'll just drill another one...