This 3.7"x 2.5" inch sticker will add that authentic look to your classic pinball, arcade or vending machine. Stick it to the glass or apron. If you are concerned about damaging the apron, blue tape could be used instead of peeling back the sticker.

Using slugs is still illegal in the United States. Here's the current law along with a history of revisions since the 1940s.
https://www.law.cornell.edu/uscode/text/18/491