I'm not working on this project, and I am not working of this project for more than the reason of my other project taking precedence. But, I am still doing this project do to the need of this project. I have thought about the feasibility of what I have described, and while this project is possible, it's not practical in its current form.   No matter how much I keep playing the concept through my head it rings of impracticability.  While the need for a 5 color 3D printer is a necessity, the way that I have thought of getting there is ridiculous to put it bluntly.  The amount of components and the functions of each of those components  is too much for too little.  So, from now on that idea to the build is going to be scrapped.  The standards will also change.  I want you to think about this for a second and tell me what you think of this system compared to what I am proposing to replace this concept.

ORIGINAL

You have 5+ filaments that are fed in and controlled with their own servos that have to be individually and maintained on untested customly made control circuitry.  You have to use and purchase all of these large rolls of filaments that take up lots of space.  Also, there be will a need to buy different quantities of different reels because a reel has to be individually used and some reels also function to do nothing but filler.  All filaments also have to individually wired to those individual pieces and make custom components for each filament that consume circuit space.  There also needs to be more separate pieces for any custom filaments that don't work with color.  No mounting system can be chained between filament reels because they are different colors.  This doesn't even begin to include the uses of speciality filaments that dissolve or get specific properties.

Then you have to appropriately mix the filaments into a chamber that get the right color at the right time.  You have to control the individual rates of each filament to get the right color achieved.  You also have to monitor the amount of each filament that you have.  

That is the jist of the original concept

New Concept

You have ONE filament.  All the color is injected via an ink or dye in a mixture chamber.  That means the only timing you have to keep track of is in the mixture chamber and you can keep a fixed interval on your one filament.  Since it is only one filament the amount of print head real estate is reduced.  You also will only have to buy one filament and you can chain them together to have more filament that is used.  You will be able to get the color in with ink cartridges.  The ink will be generic, and the cartridges will be simple to use.  All the mechanical will be at least less than half the total mechanical the other system will be.  You will also be able to have separate speciality filaments.  The ink injection system will be the same regardless of it being 3-5 colors.  

No matter how many times I frame this up in my mind, I still think my original theory of methodology is slightly ridiculous.  On one hand they would both work, but on the other hand the original concept would be significantly more complicated.  There are more moving parts, parts to buy, things to synchronise, higher levels of prediction and monitoring, and storage and design are bonkers.  When I get back onto this, everything will get an overhaul.