They are ready-made designs meant to be engraved onto glass, such as tumblers, bottles, and ornaments, rather than cut or assembled. The file gives you the artwork; a clean, frosted result depends on your glass, settings, and setup. Test on a spare piece before the final engrave.
How do you apply an engraving design to glass?
What glass items work with these designs?
Do you need a special laser to engrave glass?
What file formats do these engraving designs come in?
Can glass engraving designs be used commercially?
Do you need a rotary attachment to engrave glasses?