Cylindrical lithopane

Takes a surface height map from an image and renders it across the inside surface of a cylinder.

By the way, the proper name for these translucent etching things are "litho _ph_ anes", but I've stuck to Thingiverse usage and custom in the title.

UPDATED: allow for embossing the outside of the cylinder rather than the inside. Outside embossing appears sharper when lit from behind, but then the cylinder isn't smooth on the outside when unlit. See the last two photos.