A Connextras video on a thing with Numitrons in it

Or, if it has served its purpose, sell it on Ebay and get some money back.

You could put it dismantled like that in your set 😉 (if you really don't want to use it as dark room timer, it has something cool vintage about it still, even if the display technology kind of... sucks...)

We did it like this for small runs of PCBs using different width rolls of sticky tape for traces. Sheets of premade IC pads and such were laid down for the components. Lift them off the sheet with the blade of an exacto knife as you also used that tool to cut off the length of sticky tape once connecting point A to B and so on and so on. All were laid down on clear acetate and then photographed 1:1 to make the negatives to then used on light-sensitive copper-clad boards and usually a UV lamp. https://www.griederbauteile.ch/download/Katalog/E-Platinen.pdf and https://www.youtube.com/watch?v=YYqTCLMN_KI

The mark on the silicone sleeve looks like side of the soldering iron got too close while the adjacent wires were being soldered. Maybe put it in a clear case with filter around the tubes?

I can help with the pronunciation of SPRAGUE. They used to have a slogan in their catalogs at parts stores. "Don't be Vague, ask for Sprague" Probably TMI, but here's the Wikipedia article on them. https://en.wikipedia.org/wiki/Sprague_Electric

Basic circuit board design at that time was basically drawing your circuit on a blank pcb met a acid-resistant marker and etching it. For low-volume production you could do it with drawing on a transparent foil and use a photo resist and develop it like a photograph, then etch it. So they are wavy and look drawn by hand because they are.

Those components are RIFA filter caps. At their current age they are prone to spontaneously combust when power is attached!