Silent Cloud TECH offers a new service: laser engraving of keyboards. Fiber Optic Marker is used to apply any additional language to the keyboard. No more stickers or films are required, because after applying an additional language the letters will not rub off, the glue will not stick to your fingers, and if there is a keyboard backlight the new characters will also glow in the dark.
The color of the new characters cannot be chosen, because it depends on the key itself.
The Apple MacBook Pro key is an example:
The key is originally transparent(matte transparent plastic) painted white, then already painted black. Removing a layer of black paint by laser reveals white and you get a visible symbol.
Not all keypads can have additional characters printed with a fiber laser. Most budget keyboards have the symbols applied by thermal transfer, that is, the symbol is applied with paint and the key itself consists of a porous/soft plastic. When using a fiber laser on such keyboards, the plastic itself is burned out, as you can clearly see in the video below.
The cost of applying additional characters starts at 30 euros.