Full-color decals that illuminate when attached to a surface of an exposed light guide (e.g. an LED glow board). The photo on the left is an actual example of one made using wide format inkjet printing. It looks great under ambient illumination or in the dark. Note the numbers in each text bubble - they were added after the printed decal was attached using a fluorescent marker.
The decals work equally well with edge lighting and with the Window Puck (TM). Decals can be mass produced with licensed imagery or custom printed with a customer's unique text & imagery. In addition, there are a number of online sites that offer semi-custom printing, where licensed imagery can be combined with custom text.
Clear decals work best, whether they attach with adhesive or without (e.g. via 'static' cling or suction).