CAD files for the case ?
For DIY case it is essential to 3d print the case. I saw that STL files are available but these are impossible to modify. Can you please post STEP files ?
stl can be imported to step
@drwino I've not seen any designs available in STEP format. DXF and DWG formats are available via the link below, along with some 3D design examples.
Note Zazardev's Proto design - he managed to alter the original Proto STL at least a little as he filled in the holes in the frame.