Onshape Part Studio in Context: Master Top-Down Assembly Design

Master this whole assembly in Onshape with one original sketch only. Design the pin in a part studio in context, the top-down environment of Onshape. Positions will be defined with fastened mates. The top-down approach allows to project geometry within the assembly environment. I saw this exercise in a PDF which prepared students for the CSWA-certification in SolidWorks.