We present a new 3D printing technology in which a thin and flexible fly's eye lens sheet and high-resolution printer output are used. Integral photography (IP) is one of the best stereoscopic viewing systems available because not only horizontal but also vertical parallax can be obtained without the need to wear special glasses. As previous fly's eye lenses were thick and hard, they were quite unlike paper. We used a flexible fly's eye lens sheet made from polypropylene with a thickness of only 0.5 mm. The density of small convex lenses is 80 lines per inch (lpi). A high-resolution printer is needed to extract images that demonstrate the full performance of this minute lens. However, recent progress in printer technology means that even a common ink-jet printer meets this demand. Two kinds of lens sheets were used; one consisted of square lenses, and the other consisted of hexagonal ones. We rendered images of 3D objects made with CG from 1024 different angles, and used our software to synthesize an IP image from them. The IP image was printed with an ink-jet printer, and observed through one of the lens sheets mentioned above. We observed good 3D images that exhibited the full parallax effect.