Quoted from PhilGreg:As for masking only certain areas, I didn't do it, but you would probably need to use a cameo vinyl cutter (or do it by hand) and stick it to the back of your printed translite.
I'm pretty sure that's what the guy who made my North Star translite did:
I'm pretty sure that is what he did too.
How am I just now seeing these? These are awesome, you sir are a true artist!