In search of the elusive 0.50 diopter lens

I recently found a Kenko 77mm # 0.50 diopter lens. This is NOT a 0.5X wide-angle converter. This is a 2000mm supplementary lens used to shorter the focal length of whatever lens it is attached to -- AKA, a "close-up filter".

I would like to find one in a 55mm size, but have come up empty-handed. I've search the obvious places -- from EBAY to B&H -- with no luck. The KENKO website lists a ton of filters, but no # 0.50 diopter type. I've even tried FILTERFINDER without any luck. And FUZZCRAFT does not have one on its list either.

Anyone know of a place that might have one? I can use the 77mm one I have with a step-up ring, of course, but could really use a smaller one. It does NOT need to be KENKO, just a 55mm screw-in type.

I believe there were Proxar lenses made in 55mm. In the "Proxar" system, you would look for a 2m lens; that would be 0.5 diopter.

So you might try looking for a "Proxar 2" in 55mm.

Here is a picture of a Proxar 0.5m in 55mm but you want the Proxar 2m: