Tapping Guide (M5) for OpenBuilds V-slot

I'm building a D-Bot printer; This one: http://www.thingiverse.com/thing:1001065. I'm using V-Slot extrusions from OpenBuilds for the frame.

When it came time to tap the extrusions for M5 screws, I needed something to help me keep my non-self-guiding taps perpendicular. This was my solution and it worked very well: a guide for an M5 tap. It slips onto the end of the V-Slot extrusion and you put in your tap and start. I generally let it get going, then pull the tap, remove the guide, and