4 different mounts (2 horizontal, 2 vertical) I created for my Dell 24U server rack to clean up my cable management in my home lab.

Vertical back mount uses standard cage nut mounting point. The vertical and horizontal top mounts I have attached by tapping the existing circular holes (between the rectangular holes) with a M5 thread. For the horizontal middle mount, I had to drill and tap the horizontal reinforcement bar to use an M5 screw.