[time-nuts] TAPR Oncore M12+ kit

[Van Horn, David]

Milling internally and externally to the perimeter of the board is a price adder, but is routinely done and not expensive.

I've done round PCBs with large, oddly shaped "round" holes in the middle, impossible to drill. 
I've done PCBs where the outer corners had to be milled to a specific radius.
I hold a patent on milling out a serpentine spring from the PCB material to support a magnetic read head.  (Saved us a ton in expenses for springs, brackets, screws and cables!)

Some of these low end shops may not actually have a mill, they may only have drills.  You sure wouldn’t want to try to mill with a PCB drill bit.

If they are objecting to milling, use a different shop.