I started collecting ideas since March. I saw already the other nixie display on Hackaday.io but it used a component i wasnt able to get in germany so deided to do it with an Arduino Micro or similar. But this idea was pretty soon destroyed by the fact that i needed 16 GPIOs for my 4 drivers. In the end i decided to use PCF8574 8-Bit GPIO expander to drive two Nixies per expander.