I have a 2 track staging yard that is effectively a shelf above my workbench. It gets dusty, so I decided to make a cover. I had a remnant of twinwalled plastic glazing sheet which by chance turned out to be just the right thickness to fit over the sidewalls of the staging yard.
I made several cover units out of three pieces of plastic and four screws. They are not very sturdy, but don't need to be as they won't usually be moved.