import cadquery as cq
w0=cq.Workplane('XY',origin=(0,0,-25))
r=w0.sketch().arc((1,21),(-27,7),(2,-5)).segment((50,-5)).segment((50,39)).segment((1,39)).close().assemble().finalize().extrude(31).union(w0.workplane(offset=50/2).moveTo(-34.5,-18.5).box(31,41,50))