Hmm ... target paper feels a lot like old yellow TeleType roll paper, except perhaps a bit thicker. If you can get some rolls, cut off a few squares and try them in place of the target material and see how they do.
You might want to make a motorized roll to pull paper off a source roll, and wind it up on a destination roll, or perhaps to simply pull off a source roll, pull a known count of turns on pinch rollers, and then run a cutter across below the pinch rollers to leave a pile of perforated paper targets.
You'll need some way to protect the mechanism from stray pellets, especially the pinch rollers.
As for the printed target -- set up a slide projector with an image of a target on a slide and project it on the paper. Perhaps have a solenoid close the shutter while the paper is in transist, so you don't shoot at a stationary image on a moving paper background. :-)
To get the image to project in the right shape - take the photo of a good target from the position where the projector will sit, so the perspective distortion from the photo will cancel the perspective distortion in the projected image.
Enjoy, DoN.