A key holder with 2 screws holes to fix it to a wall.

PLA, Generic 0.25mm Draft mode profile in Prusaslicer

Model aligned at 45 degrees on the bed fo straight solid infill lines. This allows to to use the default infill direction using X and Y motors to do the infill without even changing the parameters of the infill direction. It is easier on the machine et let a better looking edges even if your filament properties are not exactly on point.

2.450mm height for the core to be strong enough and with a perfect profile fit as the first layer is 0.2mm and all the others are 0.25mm. The natch in the key is exactly at 1.95mm so it is extacly 2 layer less than the main core so all the solid infill lines will be aligned at the end of the print for a better finish. All the edges are a little rounded to avoid sharp edges