Quoted from JethroP:

Sounds like you're only painting the outside of the cabinet, obviously not the inside too. That being the case, it's easy to remove the playfield without "gutting" it, and I would recommend removing it. Just unplug it and remove it. Get a roll of painter's masking tape and masking paper and completely mask off everything else you don't want to get paint on. I paint cabinets with them propped up on a 4 wheel dolly. Makes it easy to roll outside, paint, and roll back indoors. I do the backboxes sitting on a portable work table.
It takes me hours to tape off a machine before I begin to paint. Takes only minutes to paint. I've never bought stencils. Always made my own, and have restored numerous machines to factory paint/designs.