Some of the models are designed for rigid materials and others for flexible ones. The models materials are not interchangeable, so pay attention to the file names. If you have any request on the design just ask me.
Here is the explanation of the files names:
Flex: made for elastic filaments like TPU. Tested on TPU.
Rigid: made for rigid (non-elastic) filaments like PLA, ABS, HIPS, etc. The entire model is a little bigger and the holes for the buttons are opened on the front side. Tested only on PLA.
If you set the wall width to one filament line (0.4~0.6mm) and the infill overlap to higher amount (70~100%) you could have a rough wall surface.