One obvious solution, a solution which is coming into greater and greater use almost by the hour: 3D printing. The best fidelity/highest resolutions at reasonable prices are currently achieved with SLA-resin printers. If you aren't already familiar with 3D printing, now would be a good time to get started. It's the wave of the (near) future, IMO, and can be a real timesaver. After all, Porsche uses 3D printing for some of their pistons (!), so why not give the process a looksee?
An alternative to 3D printing here might be conventional ink-jet printing. Draw the discs in a largish scale, including the lenses, scan them into any PC, shrink down, put multiple copies on a single page and print them out (in black--skip the red lens, but leave the outline). Draw and print the hoods as well, multiple copies on the same page. Glue the printed discs--you will need at least eight--to a sheet of acetate (office supply-report covers, etc) or to a stiffer card backing. Drill out the lens holes. Cut them out as simple squares and string them, bead fashion, along a suitable size dowel or piece of stiff wire. Something like a coat-hanger wire could do.
On one end of the dowel/wire, wrap masking tape--stick it to itself, not to the dowel!--and wrap it around on itself, layer by layer until it's equal in width to the diameter of the black discs. Do the same on the other end, with your stack of discs in the middle. Now squeeze the stack from both ends (with the tape cylinders) to bring them tightly together and glue/epoxy/(or tape, this time taping TO the dowel!) to keep them stacked tight.
Now...having done all this, you can file around the edges of the stacked discs until you get them equal in diameter to the tape rolls at either end. When you have done that, you can un-stack them and they should all be the same size...WITHOUT having to cut them out in circles one at a time. To do it that way would drive me mad, and would cause a large number of re-do's and throwaways in the process.
OR...you could try using sequins (black). They come in two types, hex-crowned/"cup" style and flat--you would want flat, obviously.
These:
...are 6mm in diameter, ~3' 2" in N scale*, and if they are too large, you could stack them and file them down the same way as suggested above^^^.
5 yards of those would probably give you enough discs to build searchlight signals** for 500 miles of N scale track as well....
[* I would guess the crossing light discs in that photo are 30"-36" in diameter. ** IIRC, General Railway searchlight signal discs are 36" across. Probably the same for Union Switch and Signal too.]
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You'll have to cut out the hoods individually, methinks, and roll them around a dowel to get the curved-tube shape you need, which is why I suggested printing them on paper. You can roll thin paper around a dowel or wire, but not stiff acetate.
OR...you might find black coffee stir-straws (they are available in black, as well as white and red with candy stripes, etc.), file them to shape and cut to length. I would definitely file to shape first, because you can hold the straw at one end and in the middle while filing down the other end. Cutting to length first and THEN filing...would drive me insane. Your results may vary, of course.
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Now...for the lenses and cans on the back, you have several ways to go. I know you said you don't intend to light them, but you actually could using these:
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The 1.8 mm size has a can shape on the back, and even a lens. Some of the others are even smaller, and they all seem to have the advantage (well they would, wouldn't they, since you can light them?) of already being connected to wires...which you can bend and use to wrap or glue to whatever you will use for your vertical post.
If you light 'em up, I'll leave finding the flasher circuit part of it to you.
Or...you might even try it Evan's way too:
Flashing tiny LEDs Illuminate your creations with our compact flashing color chip lights. Elevate your projects with discreet wiring and vibrant hues.
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Two speeds on the flashing, it seems: Fast and Normal.
