I created the model to hide the power brick of my LG UltraGear 34GN850P-B display (dimensions: 36x58x138mm) but it should fit also slightly smaller power supplies.

My printing settings

• Nozzle: 0.6 mm
• Infill: 30%
• Layer height: 0.3 mm
• Supports: yes (I used the fancy organic ones from PrusaSlicer 2.6 alpha, but normal ones should be fine as well)

Assembly

Put the power brick inside and screw both parts together using 4 M3 metric screws. The holes have no threads so putting the screws in for the first time requires a bit of force.