On my Geberit flushing tank I always had to unscrew the protection plate to put a cleaning cube inside. Therefore I designed an alternative version identical in dimensions but with a slot for the cleaning cubes added.

For the print bed of my Prusa i3 MK3S+ I had to cut the model into two pieces though and add some connector pins since the plate is slightly larger than the print bed.

Since I went through the process of measuring all the dimensions anyway I also added a version without the slot just in case you needed a replacement for yours but don't need the slot. In addition to that I added an STL file for both versions without the cut as well in case you have a printer with a larger print bed, such that you could print this in one single piece.

I printed with a 0.4mm nozzle and 0.2mm layer height with PETG. Nothing should need support besides the two snap latches. Your precise print settings likely do not matter due to the simplicity of the model but I would avoid PLA since this gets installed in a place where it has frequent contact with water.

I also added the OpenSCAD file in case you want to adapt it for other print bed sizes or apply other customizations. If you work with other print bed sizes and feel lost about how to customize the model feel free to ask for help. Obviously, I needed to know the exact dimensions of your print bed then.