So I have seen lots of Nixie clocks online and thought they looked great, however I didn't want to spend $100+ on a clock that doesn't even include the tubes!
So with a little electronics knowledge I hunted around the various nixie tubes and circuits. I wanted to make something a little different to the large range of generally fairly similar looking nixie clocks. In the end I opted to use Nixie IN-9 bargraph tubes. These are long thin tubes and the height of the glowing plasma depends on the current through the tubes. The tube on the left is in hour increments and the tube on the right is in minutes. They only have two leads and so make building a circuit more straight forward.
In this design, there is an hour and a minute tube, with the heights of the plasma in each tube representing the current time. The time is kept using an Adafruit Trinket microcontroller and real time clock (RTC).