I know that on this site there are Paperformers, but how many of you also like origami? I have been an avid collector of origami diagrams and paper craft plans for many years. I like "transforming" flat pieces of paper into 3D models.
I have a selection of papercraft buildings and stuff I've picked up for use in wargaming. Not exactly a hobby in of itself, but it ties into another one. I've found some nice 3D buildings adds a lot to a table.
I've got a couple origami books, including a Star Trek one. I like to make dozens of inch-long Klingon Bird-of-Prey ships out of absurdly colored pieces of paper. I also like to make angels and frogs and cranes and swans and pianos and anthuriums. And pandas.