The case for inches: 12 and 96 are highly composite numbers, so dividing a wall or a foot into thirds and quarters gives whole numbers where meters repeat.
A free SolidWorks model of a KITZ 3 inch class 300 stainless swing check valve, 12.5 inch face to face, for piping design. On GrabCAD, cross-section explained.
Thermocouple bayonet adapters modeled in SolidWorks 2017 from the AutomationDirect drawing, in every available length. Free SolidWorks, STL and OBJ on GrabCAD.
Blender 2.79 unit settings for 3D printing: inches with unit scale 0.0254 and STL export at 25.4, millimeters at 0.001 and export at 1.0, or meters with export at 1000.
A textured model from a few photos without photogrammetry: fSpy for the camera, a simple Blender mesh, baked and clone-painted photos, Materialize for maps.