A photograph is not a finished model
One frame shows only part of an object. A three-dimensional form needs the volume, proportions and hidden areas to be reconstructed; extra viewpoints reduce the uncertainty.
Basic geometry
The form is created or reconstructed. Automatic tools can speed up the start, but fine details, symmetry and joints often still need to be checked and refined.
Cleanup
A model that looks good is not automatically suitable for manufacturing. Gaps, intersections, extra surfaces and other defects are checked.
Scale
A physical size is set for printing. For technical parts, the critical dimensions must be confirmed by measurements.
Preparation for manufacturing
Thicknesses, small elements, stability and whether the part can be printed are checked. When needed, the model is split into parts and given joints.
A prototype
The first copy can be measured and checked. The digital model is then adjusted if necessary.