Customized version of http://www.thingiverse.com/thing:188358

Created with Customizer! http://www.thingiverse.com/apps/customizer/run?thing_id=188358

Using the following options:

Vanes = 6
Rings = 4
Bolt_Hole_Width = 71.5
Standard_Size = 80
Edge_Width = 2
Grille_Width = 80
Hollow = yes
Ring_Width = 2
Grille_Height = 4
Vane_Width = 2
Bolt_Diameter = 4.5