Getting a custom VFD made would be a very expensive process indeed.

If you need a very small number of segments then Dalibor Farny can make a custom Nixie tube, which is similar technology: https://www.youtube.com/watch?v=1nHkhJ52iA4 Also a good introduction to how they are made (making a VFD would be similar but more difficult): https://www.youtube.com/watch?v=wxL4ElboiuA&t=32s

Otherwise Noritake itron still make VFD monitors for industrial applications (seems they have high temp advantages over LCDs): https://www.noritake-itron.com/site2017/index.php?option=com...