Take a photo from as far away as possible at maximum optical zoom to reduce parallax effect.
Make sure camera lens is as vertical over the center of the object as possible. Notice how the walls of the screw terminals holes are not visible as the camera is centered accurately.
Make sure the picture is not rotated. Even though this can be corrected, better get it right at this stage.
Scale does not matter at this stage. Image will be scaled so real world measurements match units in CAD program later (‘calibrate’).
Z angle 90 degrees
Make sure Canvas layer is visible
Right click Canvas and Calibrate.
Make sure Canvas layer and Origin layer are visible.
Rectangle, Fillet, Move, Mirror.
Slice in 3D slicer (Cura)