Taken from Wikipedia:
A lithophane (or lithopane or French: lithophanie) is an etched or moulded artwork in thin very translucent porcelain that can only be seen clearly when back lit with a light source. It is a design or scene in intaglio that appears "en grisaille" (in gray) tones
One of my friends at my hackerspace in Northampton, Eng-a-land, called NortHACKton
(http://northackton.stdin.co.uk/blog/) is attempting to make himself a CNC so that he can carve one of these. It was while we were discussing this and how to go about making one that came up with this variation of the idea, so this instructable is dedicate to Max and I hope that his efforts to produce his own lithophane go equally as well.
Right with all of that background out the way what follows is a guide to making your own paper lithophane. I hope you'll be pleasantly surprised by how simple it is to achieve such effective results.