I can now CNC cut 1/8" brass sheet.
This might not sound like much of an achievement as CNC machines are supposed to cut metal. However, my machine was built to drill and rout printed circuit boards and has a minimum spindle speed of 7,000 RPM (goes up to 40,000 RPM).
I have found that if I use a 2.4mm diameter double fluted cutter and cut 0.5mm depth at a time, I can get a nice cut which doesn't need a lot of cleaning up.
This is good news because it means I can make all the brass pieces instead of paying someone else to do it!