Kerfmaker (M4x16mm bolts version)

ccrumpacker's Kerfmaker use M4x20mm bolts, but I only found M5x20mm and M4x16mm bolts at my local hardware stores (Home Depot, Rona,...), so I remix it.

This version use M4x16mm bolts instead, there is also a [M5x20mm version](http://www.thingiverse.com/thing:1803334)