It's amazing what you can find on Aliexpress. After some searching and keyword manipulation, I was able to find a source for led filaments at a reasonable price. I chose the 12v 38mm version for their ease to drive compared to the other voltages and how readily you can find 12v power supplies too. The filaments I chose also come in a surprising variety of colours. There's red, green, blue, cool white and warm white. I chose red because it's a nice mix of the minitron look and a modern seven segment. I may purchase some green LEDs in the future to see if I can make a VFD aesthetic 16 segment, but that's for another project!
When the filaments arrived, I could make my PCBs, which went amazingly quick because of the simplicity. All I needed to do was make a footprint for my LEDs and methodically go back to the renders and CAD I did to place everything correctly. Since I like to add details to my silk screen too, I added an imaginary product number using the amazing Garoa Hacker Clube Bold and a logo using Densmore, as well as curved traces that'd look beautiful with something like OSH Parks after dark service.
After a quick turn around of only a week, I had my boards in hand. Assembly for four digits went quickly, but I also had to be careful while I was doing so. The leds for the filaments are placed on a ceramic backer and coated in silicone, making them incredibly delicate. I'd strongly recommend using a PCB vice or even just a soft piece of upholstery foam when soldering on the back side
Using a driver board based on another person's design, I was able to test my PCBs and see how things looked. The aesthetic with out a case is amazing, but because of their fragility, it's best that I make a case for them. It'd help with visibility and contrast for the digits too, since I don't always live in dramatic two tone lighting!