UPDATE Version 5 of all 3 parts have been uploaded. The pen is now one solid piece (including the geared section), and the marker body is now female, while the cartridge is male. Additionally the thickness for all parts has been updated to at least two layers for all parts. Let me know how it goes, and give me any feedback so I can fix problems asap.After going to many art stores, and looking at a lot of websites for a good empty marker that would fit the needs of the "Penstruder" http://www.thingiverse.com/thing:5590 I decided that the best way forward would be simply to design a printable marker and attachable ink cartridge.I will additionally be providing performance results, and instructions on how to cut your own custom cut felt tips.For now I have drafted a diagram of all of the needed pen components.I welcome any suggestions that might improve the quality of the printed marker before or after I have finished making the model in blender.The idea is that you will fill the attachable ink cartridge with standard inkjet ink that will then allow the printing of as many as hundreds of millions of colors of ABS and PLS. That is at least in theory for the moment.If you are interested, I still need lots of help, take a look at the main project for the "Penstruder", all suggestions, questions, or derivatives are welcome, and very much appreciated.----------------------------- To Do -------------------------------Step 1: Determine ideal dimensions, and design object to spec in blender. Blender model has been refined to make it printable STL files now available for all three parts Step 2: Prepare and print marker.Step 3: Cut and install custom nib.Step 4: Perform and publish function tests using inkjet ink.