@m750 they are printed from vector art from online sources I found many many years ago (arcadeartwork.org), or from art I've took from scans and then converted manually to vectors. I printed them on an off white (cream almost) vinyl material to help mimic older bulbs when using leds and laminated it to cut to size clear self adhesive acrylic sheet.
probably I would reverse print them directly onto clear panels using a UV ink printer I have access to, if i was doing them again now.