import cadquery as cq
w0=cq.Workplane('XY',origin=(0,0,-20))
r=w0.sketch().segment((-50,-33),(-25,-33)).segment((-25,-36)).segment((50,-36)).segment((50,36)).segment((-25,36)).segment((-25,-5)).segment((-50,-5)).close().assemble().finalize().extrude(40)