I think the big issue would be finding paper that's translucent enough. Jeppesen uses thin paper (VERY thin...). En-route IFR charts (high or low altitude) sound cool as they are white paper, blue and black print, with a smattering of green and brown. Problem is they're printed on both sides, and the inside page (flip side) will show through. I don't think it'll work unless I'm missing something. Still, a cool idea!