Printing and laser engraving:

 
Commonly used in customization and graphic adding technology of silicone combined with plastic buttons.

With printing technology, you can add text or icons to the keys to indicate different functions or operations.Laser engraving is more durable because it permanently engraves patterns or text on the key surface.
These technologies can increase the functionality, visibility and appearance of keys.
Specific applications depend on design needs and manufacturing requirements, and these technologies can be used in a variety of different products and industries.