If you have a Panasonic Micro Four Thirds camera and a love for retro photos, the Skink Pinhole Pancake Pro Kit can instantly turn your camera into a digital Holga pinhole camera. It's a modular system that provides three kinds of "holes":
Depending on the desired effect, you can use your camera as a pinhole-, zone plate- or zones sieve camera. To a high degree the installed aperture determines how your vision is creatively interpreted in rendering an image. The traditional pinhole creates relatively sharp images with exposure times ranging from one second to several minutes. With a zone plate or zone sieve however, photos can be taken without a tripod, if the lighting conditions permit higher speeds.