Stay with me here.

For my honors art appreciation class in college, my final exam is to make a personal collage about me, without being pictures of me. Naturally, I'm including a nice big reptile section. Now, I would love to tack on one of Rosca's [first snake, my big girl] skins to the board, but the heifer always rips hers, and won't be shedding again in time. Is there any sort of non-toxic, safe ink / paint or something I can put on her belly and get kind of an "ink stamp" to show size, and then wash off? Or, do you have alternative ideas? If I can't do it it's fine, but I'm just brainstorming for my project.