import cadquery as cq

# Create a lofted section between a rectangle and a circular section.
# 1.  Establishes a workplane that an object can be built on.
# 1a. Uses the named plane orientation "front" to define the workplane, meaning
#     that the positive Z direction is "up", and the negative Z direction
#     is "down".
# 2.  Creates a plain box to base future geometry on with the box() function.
# 3.  Selects the top-most Z face of the box.
# 4.  Draws a 2D circle at the center of the the top-most face of the box.
# 5.  Creates a workplane 3 mm above the face the circle was drawn on.
# 6.  Draws a 2D circle on the new, offset workplane.
# 7.  Creates a loft between the circle and the rectangle.
result = cq.Workplane("front").box(4.0, 4.0, 0.25).faces(">Z") \
                              .circle(1.5).workplane(offset=3.0) \
                              .rect(0.75, 0.5) \
                              .loft(combine=True)

# Displays the result of this script
show_object(result)