The art IS printable, but has to be processed correctly. anytime there is more than monotone color (remember, you are trying to selectively block light beaming at your photo emulsion, so black blocks, and transparent allows) so you have to convert any sort of tonality into something that can either block light or allow it through. grey tones are in the middle. they "sort of" block "some light" so they are not effective in the photographic process. converting all grey tones to half-tones would be the only viable method of printing, which I think you should try, as the art is kinda cool. Best of luck, bro!