Customized version of http://www.thingiverse.com/thing:299663

Created with Customizer! http://www.thingiverse.com/apps/customizer/run?thing_id=299663

Using the following options:

outer_diameter = 18
diameter_top = 5.2
nut_diameter = 6.45
articulation_thickness = 1.5
opening_width = 2
height = 30
bolt_diameter = 3.2
diameter_bottom = 5.2
pressure_point_thickness = 4.5
washer_diameter = 5.8