Thank you very much for your reply.

So in Poland is now cold, I gave playfield for car painter and will be painted in the spray booth, we did tests with the paint and it worked out pretty well.

I do not quite understand what it means to "its best for the NON LAMINATED ones"

Some of the sticker inserts get a clear of some sorts in them when made. They have a shiny appearance. The non laminated ones will have a flat dull appearance.

Your car painter should be fine in theory is no different to a car. When spaying over the sticker first coat should be a very light almost dry,  then following coating can be thicker.

Good luck.

Would love to hear about the Polish pinball scene in another thread!!