For the sake of simplification (and sometimes complexity), the usual fillets due to the molding of the part are not always represented.
In the different sketches, for clarity only the dimensional constraints are visible.
Procedure or construction tree :
The construction timeline is very important in a project.
My approach is defined on the pictorial tree opposite and is based on the interdependence of forms as I perceive it.
<<-- To consult these different steps, click on these images.