It's Friday, it's beautiful outside, I'm stuck at work (and yes, I'm doing my work... don't worry).
My first wild idea is, how thick of a carbon print do you think you could make? That is, how high of a relief?
I mean, like 1 inch, 2 inches? Imagine a glop with much less pigment than what works for typical coatings. I'm thinking to pour a solid "cake" of gelatin in a form/dam that is at least 1 inch deep or so and letting it dry for the necessary time (a week or more?). Then, expose it through the base, because transferring seems out of the question, and if you're pigment concentration is just right, you might be able to get a humongous relief. Almost to the point where it's a sculpture.
2nd idea; anyone ever made a carbon print with finely ground coffee as the pigment? That might smell nice.... what else could you use?
Talk amongst yourselves...