Each one is custom made by Custom-Metal in Germany ¹⁾

The headlight shell came from an old $3 brass (or brass-plated) lamp at a local thrift store.
With some cutting and grinding, it turned out to be sized just right for the stock Harley headlight and its rubber mounting ring.
A few light coats of Duragloss candy copper paint (translucent) and a couple coats of clear was used on the OEM headlight rims.
Wiring is hidden under the tank.
The mounting bracket was made out of some scrap billet. ²⁾

This particular brass cover is made by Kijima in Tokyo.
It was bought from Webike.net in Yokohama. ³⁾