The cost of recreating one vintage lightbar alone would bankrupt anybody who would attempt to do so, let alone every single vintage lightbar. The market is so small that it wouldn't make sense to even try. While it may seem as if there are several vintage lightbar enthusiasts, there really aren't that many to justify trying to manufacture parts to recreate vintage lightbars.
Forgetting for a minute everything you'd need to make domes and lenses, you would need the machinery to make all the other small metal plates, screws, clamps, brackets, and fittings that make up the guts of the bars.
This is spot-on,
IMO. Factoring in what's involved in even a more basic "classic" bar, you still have a ton of production involved. I'm taking a guess here, but much of the machinery and/or molds needed to manufacture even the most basic parts (e.g. a rotator gear), in addition to raw materials (e.g. aluminum, plastics, etc), in addition to production machinery design, maintenance and operation costs plus the costs of hiring, training and paying assemblers, even if there were only a few of them, would be huge.
Now, take a rarer and/or more complicated bar where the molds/designs are long gone, the original production machinery long-scrapped and the production specs long gone and things get even more costly. Throw in the costs of the redesign and production of even the most basic things like a gear, and those costs go up even further. I'm by no means an expert in industrial production, manufacturing, design or processes, but there's a shocking amount of time, labour and money involved in making even pretty basic stuff.
That and the other big downside would be that these bars would be reproductions, more or less. They wouldn't really be the real deal. That and it opens the floodgates for really cheap knockoff copy reproductions. Take a look at anything collectable where reproductions are made; there's usually a saturation in low-quality knockoff junk and copies. Not to mention reproductions being passed off as the real deal. It really opens the door for scammers and crooks like crazy.
That, and it's a copyright and patent litigation nightmare.
It's a wonderful idea, it really is, but it's just not feasible and as I see it, risks saturating the market with overpriced garbage knockoff reproductions, making the terrain even trickier for collectors.