Customized version of http://www.thingiverse.com/thing:976416

Created with Customizer! http://www.thingiverse.com/apps/customizer/run?thing_id=976416

Using the following options:

Proofread_Spring_Diameter = Yes
Right_Hole_Diameter = 8
Spring_Left_End = 0
Right_Hole_Type = 6
Spring_Coarseness = 80
Spring_Right_End = 0
Spring_Length = 30
Spring_Wire_Diameter = 1.2
Left_Hole_Type = 6
Spring_Windings = 7
Left_Hole_Diameter = 8
Spring_Outer_Diameter = 9.1
Printing_Helper = Yes