My last shelf required a double-wide cubicle set up with a seam between insulating panels. If all you have are corners I've still got you covered. This half width shelf works the same way and like the one before it prints without supports. If you want to have one for the opposite corner just go in your slicer and select mirror on the x axis before slicing. The hooks are spaced to work with Steelcase brand cubicles but they might work with other brands.

The example in the photo was printed at 0.3mm layer height with no supports.