Introduction: 100 Yen Racks, Multipurposed
This is a pop-up shelf available in 100-yen stores in Japan. I'm sure there are equivalents in stores around the world. I have a couple in place in their intended configuration, but most of mine are upside-down...
--used in a closet space to mount all internet hardware out of the way. The wall side is fastened with two U-tacks and the fore side with two screw-in hooks.
--mounted under a table for the same purpose, fastened with zipties.
--hung under a kitchen shelf for an easy and breathable cutting board rack, held with S-hooks and zipties.