What can I do for a science project on the effects of the sun on your skin?

I need to have something that people can look at along with a poster board. I was thinking about using some kind of material and cover one with baby oil, one with sunscreen, one with nothing, etc. What kind of material? Any other suggestions? (Oh, and I only have a month :))|||You can buy photosensitive paper (can be found at craft stores, art supply stores, or online) and expose it un protected, covered with cloth (to represent skin covered with clothing), covered with sunscreen, etc. And one that has not been exposed as a control. The sunlight changes the color of the paper. You can also find pictures of sunburn on people, plus the effects of too much sun exposure: wrinkled, leathery skin, sun spots, skin cancer, etc. Be sure to include both the good (vitamin D synthesis) and bad (burns, cancer) aspects of sun exposure.