Hot-swap Pen Holder

I saw Tech2C's video about drawing on a 3D printer recently and thought I would give it a try. I was toying with the idea of pausing the print and using different colored pens to give a cooler effect so I designed this drop-in replacement for the e3Dv6 hotend that would allow hot-swaps between pen cartridges during a printer pause. It will hold cartridges from the Pilot G-2 series ballpoint pens and should be at the right height so that you don't have to adjust the limit switches on your machine