Im not certain but Chris Franchi is a natural born Artist not a computer program guy. His art comes from his talent, a pencil, and a brush. No photoshop tricks. What they use to scan his final art with I have no idea but having seen some of his work in person Stern is lucky to have that man on board. Truly changed pinball playfields for Stern in my opinion. And he's a really great guy which is nice to!

Going to be a big difference between modern art and older games. These days just about everything is CMYK process color, with a white undercoat. Playfields and plastics are essentially inkjet printed. Certainly still possible to do spot color, but it's an added expense. I'm not aware of any current games that aren't done with CMYK as the base at least.

Everyone has a different process, I can only speak to my personal experience, but for Alien I imported the CAD drawings into Illustrator and used that as my starting base. All of the 'hard line' elements like the inserts were done there too as vector shapes. They were all imported eventually into Photoshop as smart objects so I could edit them later, and the final full color art was a 300dpi TIFF exported from Photoshop. Anything white was 'transparent', the base coat does the white.

The white layer was a vector shape from Illustrator. How Mirco does the printing. So final print is a combination of vector and raster art technically.

I do some things differently if I ever did it again, just to make my life easier going back and forth between Illustrator and Photoshop, but I'd still use both to create the final outputs. My guess is that's pretty common for everyone these days.