Rasberry Pi 4 Model B Case with snap fit mesh lid

This case has 4 versions: 

• Plain: No cutouts and no mesh
• Plain cutouts:  This version also has no mesh but it has slits for GPIO and camera cables
• Mesh standard:  A mesh is added in PrusaSlicer to the 3MF files. This only works when you open the 3MF file in PrusaSlicer. The mesh is only visible after slicing! 
• Mesh risky:  This new version contains the mesh inside the STL itself. This is more difficult to print because the slicer has no idea that there is a pattern and it just prints individual tiny hexagons. Version requested by @GijsPrins_1635555