Keytops
Keytops are used on full-travel keyboards. While modern keycaps are typically surface-printed, they can also be 2-shot molded, laser printed, sublimation printed, engraved, or they can be made of transparent material with printed paper inserts.
There are also Keycaps, which are thin shells that are placed over keytop bases. These were used on IBM PC keyboards.
Read more about this topic: Keyboard Technology