Step 11 : create the skylight left wall plate (new body) then the right by symmetry

In this new body, create a shape binder from the facade of the roof
of the skylight.

In a new sketch created from the shape binder, create the geometry
of the left wall plate of the skylight.

Create an extrusion with a length equal to 600 mm.

 

Create the right wall plate by symmetry / YZ (Part WB tool).