Mostly Printed CNC Roland Drag Knife Holder

After having given Allted's Liyu/Roland Drag Knife holder design a try:
http://www.thingiverse.com/thing:780877

I found it was limited because the drag knife could not float over the surface. If you use a cutting mat under your material like I was, you'll find they are not perfectly flat. When material thickness is measured in thousandths of an inch, this means the cutter will constantly be lifting and crashing across the material, resulting in incomplete cuts and material snags. I found a creative solution here:
http://forums.zentoolworks.com/viewtopic.php?f=17&t=2636

...which allows the knife holder to float across the material surface under spring tension and travel a couple of millimeters to account for an uneven work surface. So I refined and adapted that design along with Allted's blank tool holder part for his awesome MPCNC design. With this assembly I've been able to use the machine as a vinyl plotter now to create over 60 feet of painting stencils for an arcade project I'm working on. An attached photo shows the detail I was able to achieve with this attachment, which I am very pleased with!

I am using auto bed-leveling in combination with this tool to improve the performance, but don't feel it's necessary if your work surface is nice and level since the head can float a couple of millimeters. My toolchain is as follows:
1) Design in Inkscape
2) Save as DXF
3) Convert to Linux GCode with DXF2GCODE (drag knife tool selected) http://sourceforge.net/projects/dxf2gcode/
4) Convert GCode to Marlin GCode with a custom utility (most of what it does is comment out gcode commands unsupported by Marlin, and changes the formatting of movement commands)

Thank you Allted for sharing your CNC design!

EDIT: incorrectly listed M4 fasteners previously. Updated to M5.

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