Tonight I opened the
#Pinephone back cover CAD file in
#FreeCAD to check it out, as I want to design a case with a quick access battery door. Unfortunately I found with a geometry check that the STEP file imports with a sh*t load of geometry errors, it's considered an invalid solid. That makes editing it problematic.
I'll have to see if the commercial CAD software I use at work can repair it. Actually I've had the work PC home since March. But booting it on a weekend? Bleh. (It's running Windows 😉)
It's possible. Conversion from a geometric kernel to another (Pro Engineer's Granite to STEP to Open Cascade in this case) is often problematic with non-prismatic shapes. The case's rounded edges are part cylindrical, part B-spline surfaces.
Were your programs made to fix STEP models?