This is a case used to mount an LM2596 buck converter to a Creality Ender 3 (or Ender 3 Pro). This is most often used to bring the 24V from the power supply down to 5.1V for a Raspberry Pi running Octopi. This case was built using the Valefod version that was purchased on Amazon; PCB measures 62mmx35mm.
While there are already some cases for the LM2596, none of them that I found had the rail to attach them nicely to the 20x20 extruded rails. Not only did they not have a rail, but they all looked kind of gaudy and over complicated; so I designed my own. This case has plenty of air flow and gives you full access to the power points on either side. The top just lightly press-fits into the case, there are no screws. The PCB sits on posts built into the case. The PCB fits very nicely in the case, keep this in mind if you are soldering wires and not using the screw terminals for power.
I have included the STEP files for both the top and bottom of the case in case anyone wants to remix these or modify them for their own use. This may be required if your LM2596 is a different brand and they use a different footprint for their PCB.