How would this get made effectively?

[William Wonkum]

This company makes custom labels out of this rubber/silicone material. How can they achieve that? With a mold that has adjustable letters? Like a printing press where different letters can be taken out and rearranged? Or does the rubber/silicone material get made in mass quantities blank, then heated up and stamped? Reference website: www.inchbug.com

 

[Chuck Lee]

rubber/silicone is thermosetting.
so I think those words or icons were laser etching