How are pinball backglass reproductions made?

There are a few different methods that have become popular and a new one that has been name the "layered backglass"

The layer backglass approach involves creating art from scratch using a program like illustrator and recreating the backglass. This method allows the art detail to remain as well as eliminating any damage the original has like granulation and peeling. The high-resolution art is created in multiple layers to ensure vibrant colors that pop and to avoid hot spots when the back lights are on. The image is measured to ensure accurate graphics and score boxes. Finally, it is sent to a state-of-the-art printer that can print in all those layers.

The next method is called a translite. These are where the image is printed on a thin membrane and then sold as a DIY option or adhere4d to the glass before shipping

Finally, there is a method where the original backglass is scanned, touched up and printed on a label which is baked in an oven at high temperature to adhere the label onto the glass and remove all bubbles from it.