Vacuum Powered Fluidic Ink "LEDs" and Circuits : 15 Steps ...
For the "control layer" I used a 2 mm diam flat end mill to first mill the screw holes. Then I turn the plastic plate upside down to mill the control chamber on the backside still with the 2 mm flat end mill mounted. Then I turn the plate upside down, realign th part, and mill the conical tube connection hole with the 1 mm diam ball mill.