Ok, it's just 0.005" / 0.12mm shim stock. But brass is harder than copper and 0.005" is thicker than 1oz copper cladding, so that's a capability expansion.

Cut with a 0.1mm 30° V-bit.

Cutting more substantial brass stock with an actual milling cutter remains to be tried.

... and just for fun, I tried skimming the side of a razor blade:

That produced a very small pile of metal slivers, so it wasn't just scratching the steel. Interesting. I didn't try to do any more with that today. Also interesting: at this scale, there's enough magnetic attraction between the steel blade and slivers thereof that the slivers don't leave the immediate area around the action. Convenient because, not expecting to cut anything ferrous or particularly hard, I haven't given much thought to keeping magnetic or hard bits out of the works. Dunno if the blade was already magnetized or magnetized by cutting.