All the parts can be printed with PLA filament there is also a SVG file for the front so you can use a plotter or a laser cutter, also the back and main case can be laser cut as well i think.
The nixie kit can be found here its a really nice made kit with good instructions and all the parts are labeled! Got mine a long time ago when he stared selling them for a discount price but its really worth it specially for a beginner it's maybe the best kit i have build!
For a smooth finish you can use this neat trick!
Buy some flat picture paper (a4 sheets NOT Glossy) sand the outside of the 3D parts slightly with sandpaper grain 220ish then use a contact glue like 'Bison Kit' and glue the outside of the 3D parts and the paper let the glue dry and then press them together for the contact glue to set now trim the edges and inside and you are ready for painting!
The Paint i've used
-To get the blue color mix some Tamiya X14 (sky blue) into Tamiya X2 (white)
You can use a paint roller with these paints, or a airbrush if you use a airbrush you need to thin the paint! Use Tamiya X-20A Thinner or mix you own with 30% isopropyl alcohol and 70% water.
-Vallejo Satin varnish as finish
BOM (Bill Of Materials) i've used
-2x 10mm tac switch
-Metal mesh for the inside of the housing these are leftovers from a broken electric mosquito killer :)
-Some power wire 22-24 awg or something like that
-Nylon hex spacers to hold the pcb and the back (you can use CA glue for them)
-4x m3 nuts
-->My case had a design mistake where i could not screw the back in place the files you are downloading are updated so you can use the screw holes!
-->The 2 white connectors for the tac switches (as seen on the pictures) are not necessary.
Have a good day.