For the upcoming Mercury solar transit, or solar eclipse, this will help aiming your camera safely at the sun. Just insert it in place of the flash, and look at cylinder shadow. If you see a shadow, you are not aligned. Move your camera until the shadow disappears. Do not forget to protect your camera lenses with mylar film (Astrosolar in this case). With this device, you are always looking opposite to the sun, so the is no risk for your sight. Print both parts, insert one side of the square in the base slot. It is printed with 0.2mm layers I used the hotshoe insert from http://www.thingiverse.com/thing:25382
Enjoy!