import cadquery as cq
w0=cq.Workplane('YZ',origin=(8,0,0))
r=w0.workplane(offset=-18/2).moveTo(-36.5,0).box(27,20,18).union(w0.sketch().segment((0,2),(25,-25)).segment((50,-2)).segment((25,25)).close().assemble().finalize().extrude(1))