I am currently working on a construction site. There are many engineers working in the site office ranging from Radio / TV studio outfitters to wiremen, IT folk, AV engineers and broadcast engineers. Being a building site all personnel including visitors are required to wear Health and Safety attire including safety boots. The storage of the various different sizes of visitors shoes was becoming and issue. When the site office gets moved to a different part of the building, as it frequently does, transporting the shoes and keeping them as pairs was also a problem.
The shoe storage solution needed to be large and preferably mobile.
The engineers put their heads together and after a few minutes decided that this would be the best solution.
A spare 42U rack, a few 1U shelves and a handful of cage nuts, job done. It's called - wait for it - the "Shoe Rack"
Since we were never allowed to attach anything to the walls, it also doubles as a notice board.