First, you need artwork! There are tons of image files already available online, from other pin collectors, using photos from NOS playfields, scanning images, and even re-creating artwork using photos of original images as reference.
For example, this is a hi-res photo of a NOS lower playfield for Haunted House that was graciously provided to me by the playfield owner. Once sized correctly, then it was just a matter of adjusting the printed colors to match my playfield before I printed the overlays.