Simple Pen-holder prusa i2

Inspired by another holder, I made it bigger, so it fits the belt screws of prusa i2 x-carriage. First step in making a PCB plotter.

I'll be using the pen holder with this x-carriege http://www.thingiverse.com/thing:49753/#files
But if you have long enough screws you can use it with the original x-carriege as well.