I had folded a 4-D origami tesseract. But then I unfolded it into a 3D tesseract that has 8 cubes. And now, I cannot remember how to refold it back to a 4D tesseract. :) You can see my unfolded origami tesseract at: http://www.flickr.com/photos/chengchit/3120433792/
Cheng Chit
