Customized version of http://www.thingiverse.com/thing:48235

Created with Customizer! http://www.thingiverse.com/apps/customizer/run?thing_id=48235

Using the following options:

_base = 0.5
_spacing = 1.2
_rows = 2
_cornerRounding = 4.0
_diameter = 10.6
_columns = 4
_height = 8