If you are good with photoshop and/or can find the art online you can try this
http://www.printmoz.com/backlit-posters

You will still need a mask. I did a Williams single player for $60 ($30 x 2 ) and $27 for the tempered glass.

Just know that I didn't have high rez versions of of the BG, I used some that I found online in an image search. I resized it in GIMP to 21.5" X 25.5" and it scaled it pretty good, but it's not as crisp as it would be with a higher rez scan to start with.

Not great pics, but..

IMG_4687.JPG

IMG_4685.JPG

photo 3t.jpg

The mask is the same image just modified.

SE_MASK_COLOR.pdf

I can't take credit for that. This is a BGResto image that they sent me when I was looking into having the SE backglass done, Since it was low rez it was ok to use as the mask, the front side I had to use my own. I hesitated to post it but I wanted to show what a mask would look like in vinyl. They keep the color in the mask so that the color doesn't wash out when backlit due to it being vinyl. If you want it brighter, you can convert the mask to black and white, but I figured they would know more than me about this, so I went with the colors. You need to use brighter lights in mine, but then again, BGResto may use different methods or materials than PrintMoz.

If this was a keeper game, I wouldn't hesitate to use BGResto as it comes with the glass and in full resolution. This was just something I threw together as a xmas present for the wife and daughter, mostly the wife and I as my daughter could care less about pinball.

Just to be clear, PrintMoz is just a printing company, they know nothing about Pinball. If you already have a BGResto backglass I would just call them and see if they could send you a color mask. I'm not sure how they assemble them, but you may be able to swap it out.

Vid1900 turned me on to them, credit goes to him Please post some pics when you have some done, I'd love to see it.

I went with gloss. Backlit poster. I sized my image to the exact size(21.5x25.5) and then requested that they cut it to that size in the order comments. They have live chat so you can ask them any questions while you order and that's what they told me to do. There was one side that was about 1/16 too long, I just ran an exacto down the edge using the glass as a straight edge.

More info here https://pinside.com/pinball/forum/topic/spanish-eyes-backglass-scan