A 17 key circular macropadFirst circular PCB I have had made. It is under 100mm in diameter so can be had for $2 plus shipping from EasyEDA.com / JLCPCB.com. Planning to order one with black soldermask from JLCPCB.
It is running firmware from kbfirmware.com. The JSON file with the pinout is on github. The gerbers are also on github.
Installed red and green LEDs. They are controlled by a MOSFET, the same as in the Gherkin.
Top of the PCB.
Bottom of the PCB. Socket Pro Micro, MOSFET and reset switch.
Second PCB used as the base. 6mm M2 screws and spacers.
That's no moon.