Here's a Gottlieb Touchdown I worked on a few months back. I pulled it out of a dilapidated warehouse along with a second machine. The playfield was pretty rough--lots of wear down to the wood around the pop bumpers and the inlanes. Because of the complexity of the artwork and the time crunch of prepping it for a show, I ended up creating decals for it. So, the goal here was to end up with a decent-looking player's pin--not to do a high-end restore. There were too many other cosmetic problems with the backglass and cabinet to invest the time in doing that.
First I stripped the playfield. Because this scanner is so large and the bezel around the scanning glass is so large, it is tricky just to scan one small area. Basically everything has to come off the playfield--including the ball guides. But, I sort of lucked out in that the ball guides that would have been in the way were broken and needed to be removed anyway. PBR had replacements available.
Next, I scanned the areas that needed attention at 600dpi. I like to scan at 600dpi since it grabs the most amount of detail as possible, and you can always scale down for printing. the downside is the filesizes can get quite large, expecially when working with these images photoshop.
The best scans were made with the lights off. This prevented color shifts, light bleed, and shadows from showing up in the scan. Scans should have about 2"-3" of overlap so that they can be merged later in photoshop. I also took high-res close-up photos of another game, which I used as a reference to re-draw the missing areas that were worn to the wood.
Then the scanned images were merged with photoshop using file > automate > photomerge. Select the "reposition" option so that the images don't get curved or distorted like with a set of panoramic images. If the images don't line up properly, use the "interactive layout" option and position them manually--photoshop will take care of the stiching when the photos are close enough together.
Before getting too far with Photoshop, I did a fast-draft test print to make sure the scan lined up properly, which it did.
Then the bulk of the photoshop work...
After finishing the photoshop work, came fitting and printing everything on white waterslide decal paper with a laser printer, and adding each piece to the playfield. It is best to print from a cold start on the laser printer, rather than after it has been sitting there for a while baking. The extra heat can ruin the decal paper. Laser printers can typically cost $250-$600.
The paper comes in white or clear. Clear is generally only used for adding black text over inserts. White is generally used for everything else
To prep the playfield, you can use a filler material like JB Weld and use a soft rubber edge to smooth it level with the paint on the playfield. For whatever filler you use, make sure that it is either a neutral gray, or paint over it with a neutral gray. Otherwise, it will show through the decal. For a more detailed guide on filling wear spots, a thread on The Shadow's sanctum repair may be useful: https://pinside.com/pinball/forum/topic/shadow-sanctum-repair-updated
After that, I waxed the playfield and let it sit for a few hours. Since water is used to apply the decals, this would hopefully prevent planking.