I love how origami diagrams make for an art form of process and reproduction.
Indeed, I mostly fold from diagram and I am building a huge collection of origami books. I am a biologist and nerd, and my favorite subjects to fold are animals and mythological creatures, especially dragons.
However, more than anything else I love researching, buying, dyeing and treating paper, always looking for new material and different methods. As I dye more than I can ever fold, I started selling paper on Etsy.