Here is my nixie clock :

6x IN14 russian tubes
6x Neopixels Leds
2x HV5530 high Voltage drivers
1x 210V High Voltage step up power supply
1x 5V step down power supply
1x ESP32 microcontroller
1x radar sensor
1x light sensor
1x (option) temperature + pression sensor
2x home made pcbs

And one Android application speaking to the ESP32 with Bluetooth Low Energy

Just add a piece of wood (from Vietnam :)) a CNC mill, a 3D printer (for spacers and leds' light under the tubes), one lathe (for aluminium rings) and a lot of hours.

see it in action here : https://www.youtube.com/watch?v=7I_mB28OVZ8

The heart of the system is an ESP32 MCU. It drives the 2 HV5530 drivers.
These drivers are powered by a 210 V DC step up converter. I bought this Power supply here : https://vfdclock.jimdo.com/2015/07/18/openhardware-10w-mc34063-based-high-voltage-power-supply-module-high-efficiency-small-size/

The main DC voltage being 12V DC.
5V is needed to power the ESP32. A tiny step down converter is added.

6x Neopixels Leds are used to produce light effects

radar sensor allows to switch off the nixies when nobody is there (7m meters motion detection)
light sensor allows to dim the nixies.

the two boards are single sided and mounted one above the other to let the LEDs light penetrate the bottom of the nixies tubes.

The nixies are directily soldered on the top pcb.

The radar is mounted on the side, facing the clock.

A wooden box is milled to cover the electronics. Absolutely no buttons is visible nor needed as the interface with the Android App is done via Bluetooth low energy.
Using BLE allows to avoid pairing between the clock and the phone.. Everything is "no plug and play" :-)