Allows your GoPro to be mounted on pretty much any tripod (i.e. if it has a little bolt coming through the center of it).
I found the great looking design by jpmurph didn't quite work for me when printed on my Replicator.  I was able to fix up the STL file in Blender and now it works great!
The bug I found was that the hex nut hole was 20% too small and not far enough recessed to allow bolt to solidly connect with it.  I also shortened the base a bit, to be more minimal and snug.
One-click nuts:  http://www.amazon.com/gp/product/B000FMUA76/ref=oh_details_o00_s00_i00