The Cling Mount is a great thing to have, especially if you need to hang things on a flat surface.
From The Manufacturer:
The Cling Mount is an all-in-one mount designed for use on smooth flat surfaces. The Cling Mount uses advanced suction to hold up to 50lbs each. Combine with Mattos Designs Push Mounts to switch props with just one push. It couldn't be easier! Check out the full line of Mattos Designs Mounts for all your mounting needs. Mattos Designs Mount Systems - The only mounting designed for what we do.