I have only seen one machine in person with an overlay, it looked like crap

the trick is you need to stick it down perfect, so there is no bulges or bubbles
where the inserts are means there is another layer for the light to shine through
there is also the color matching for the person who did the overlay


If a playfield was toast, the wear was larger than a business card, and there was little chance of a reproduction being made (ie any Gotlieb game) then sure, make an overlay