Customized version of http://www.thingiverse.com/thing:511489

Created with Customizer! http://www.thingiverse.com/apps/customizer/run?thing_id=511489

Using the following options:

bottom_length_text_box = 60
height_text_box = 30
top_width_text_box = 40
relief_thickness_text_box = 2
top_length_text_box = 53
relief_height_text_box = 0
steps_text_box = 20
top_corner_radius_text_box = 5
bottom_width_text_box = 50
bottom_corner_radius_text_box = 5