I have gathered some links for making plastics (along with my own
experiences) at the bottom of my BOP page:
http://www.edcheung.com/album/album10/pinball/bop.htm
Since with plastics, the concern is the amount of light from front lit
and backlit sources, it can be hard to find the right media and print
method. I found that inkjets were not saturated enough, and
waterslide let through too much light from playfield lights. In my
experience, printing with a laser onto white paper produced the best
look. Take a look at the various approaches and decide for yourself.
Edward_Cheung CARGPB26