Hello Yossi, I just now found your thread, and might have some advice to offer. If you are not able to find an original exact reflector for your headlight, you might can fabricate one inexpensively at home. It might not be totally exact to the original, but it would be close, and would work and look good. Oddly enough, on a lot of these 1890s bicycle headlights, the reflectors are often not made of nickel plated brass like the rest of the headlight is, but are instead made of polished aluminum. Aluminum was viewed of as an advanced and futuristic metal in the 1890s, and that is part of the reason why it was favored for use in this way at the time, in addition to its corrosion and heat resistance. What you might think of trying would be to go and buy a canned drink like a soda, and choose a can that looks close to the diameter you need. You could then, with scissors, cut out the bottom of the can which is concave like the original headlight reflectors, and then fabricate a new reflector from that. The aluminum would already be quite polished and shiny, and could be polished more, and if done right you could probably make a really good quality part. The thickness of aluminum in most drink cans is comparable to that of the original reflectors. That is just an idea that you could try, if all else fails, or if you want to save a little money. Here is an example of the can you would look for:
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