3-D structures which are fabricated by gray-tone exposure of a class of thick negative photo-sensitized epoxy resists from the substrate side of a transparent substrate, using development methods that rely upon a physical distinction between polymerized (solid) and unpolymerized (liquid) photoresist...http://www.google.de/patents/US7303853?utm_source=gb-gplus-sharePatent US7303853 - 3-D structures with smoothly-varying topographical features in photo-sensitive epoxy resists
