I am not an absolute expert on printing technologies. However I have been in various levels of computer technical support for over 15 years. This leads me to a couple of disagreements with the original poster on what will and will not work.

First and foremost, I am very skeptical, of the whole idea, of putting fiberglass through a printer. The thought of what might happen to your printer if the glass cloth started to unravel in the printer is enough to give me the heebee-geebees.

Second fiberglass does not strike me as a real good image substrate. Fiberglass has a very uneven surface. This could degrade the quality of the image. Also normally the glass disappears when wetted out. However when it is printed on the colored ink could show the weave after the glass has been wetted. Finally fiberglass can be stretched unevenly when it is wetted out. This would cause the image to be distorted.

As far as what type of ink, dye, or toner to use, here are my thoughts. I put these items into three basic categories.

Wax based Water based Granular Toner

The Wax based color systems should be avoided at all costs. It is highly likely that they will interfere with the bonding of the epoxy. Wax based systems can be found in a lot of printers that lay color down from plastic sheets or ribbons. Some Techtronic printers use a waxy crayon like stick that it melts and sprays onto substrate. If you run your finger across a printed sheet of paper you can feel the raised almost sticky wax from these systems.

Water based inks are what you will find in most "ink jet" type printers from HP, Epson, and Cannon. The best way to test is run some water on a printed sheet. The ink should dissolve and run. I haven't tested these with, epoxy however they should work. They do fade with UV, so I would be careful with how I would use them. One thought would be to wet them out under your varnish coats rather than under the fiberglass. This would allow you to sand out the image when it fades beyond your liking.

Granular toner from a black and white laser-printer is non-waxy, water resistant, and fad resistant. It should work well on tissue paper under fiberglass. I am not sure about the color based toners, they may be wax based.

Don