IanJohnson, it colors from the top with the tip, not from the side. The tip is flexible enough that it tends to wrap a little around the filament. End result is even if painted from top it looks solid enough.  An inkjet would paint the entire filament, it does not need to soak in from above. When seen from beneath, which I imagine is what you meant, it does look a bit lighter, but the filament is a little translucid anyways (I used white PLA).  For painting arches I imagine using transparent plastic, either the whole object or with a double extruder put an external layer of transparent plastic, paint it, and continue with white plastic. If you put a layer of transparent skin all around the object it will protect the ink as well.

Marcelo

Thanks!

The company you are referring to is MCor. I saw them recently at the Inside 3D Printing Conference in Brazil, and their machine is impressive. First they print a whole ream of paper, then they slide it into the machine that cuts the perimeters and slashes the remainder, so it's easily removable by hand when done. Each sheet is put on top of the previous one, aligned by optical registration marks, and glued (dense where it's object, light where it's support) to the previous one. When finished they infiltrate it with metaacrylate plastic and the part is really very solid, even more than FDM prints, and full color with extreme detail.  The main drawback is you have manual postprocessing to remove paper, and you cannot remove internal support easily, so you could not print an Eiffel Tower, for instance, or a Torus.  But for most real objects, it's nice.

Please provide any links to previous similar projects, I'd love to see them.  The next challenge is substituting the markers with an inkjet, then the color will be full spectrum and more precise, quicker.  With that it should compete with Mcor, but at lower cost and with more versatility, since you could still combine multiple materials (hard and soft, plastic and dissolvable support, etc.) but get full color objects. 

Any investors out there? :-)

Regards,

Marcelo

I have seen some reprappers do similar work, in preliminary stages. I hope you have the chance to learn from their work too. I am glad it sounds like you worked through a lot of the software heavy challenges.

There is also a 3D printing company that works in a similar basis. They use layers of glued paper, and cut out the appropriate "layer" as needed. They then run a somewhat standard inkject printer over the perimeter to make infinite color combinations. I've only read about them when I heard the company staples was going to use their machines. I remember them as scottish or irish, but haven't heard anything about the company since. Also, I have not done much searching.

Regards,

Marcelo

http://3dprint.com/3340/ulimate-filament-colorer/

Here was my original PM to a few guys here in Dec-2012:
The basic concept is to apply liquid pigment to the outside the white filament just before it's fed through the hot end.  I'm fairly certain that the amount of area you'd cover with pigment would not be enough to create any deep colors, but the thought was if you could set up 3 inked rollers that could move in and out based on the color being called for each covering 1/3 of the diameter of the filament you could create any color by mixing the 3.  Since pigmentation of ABS is done by melting the ABS and adding a dye, could it be possible to add enough dye to the outside of the diameter that during the extrusion process it would tint the filament, would red dye yield pink extrusion? 

If this concept or a derivitive of it could work, then I can see someone with vastly more knowledge than I have making a toggle to bring the pigment in and out of contact while the printer is operating.  You'd have to know the distance between the ink placement and emergence from the extruder tip but I think you could come up with a pretty good estimation based on your feed and flow.  Pronterface will read in how much material is being used per print so I know the calculation is already there.  You would need cooperation from programmers / electrical hackers, and mechanical hackers to make it work. 

But it all hinges on a simple test of applying pigment to white filament and watching it go through the hot end.

Kikai Labs, a desktop 3D printer manufacturer based in Argentina, has developed a new accessory that allows a 3D printer to paint multiple colors of your choice, while printing, using magic markers.

The current desktop 3D printers rely on multiple printheads with different spools of pre-dyed filament, so users can only switch colors per layer and they are likely stuck printing in two or three colors. And full-color printers are really expensive. Two students at the University of Wisconsin-Madison have come up with a sub-$100 device called Spectrom that adds dye to the plastic as it melts, allowing printers to print in a full colors, but apparently only whole layers at a time, as is the case with BotObjects as well.

Kikai Labs' approach involves a combination of self-developed hardware and software. The method allows for very precise painting, including lettering and even photographic reproductions, at a very low cost.

Integrated into the hot end head, this system includes precision servo motors and 3D printed parts that hold more than three markers. Kikai Labs developed their own colored-object slicer which works with Slic3r and run independently of each other.

This approach is still limited in detail and in number of colors it can apply. But the technique will be refined further and eventually the part will be offered as an accessory on their new line of FDM printers, says Marcelo Ruiz-Camauër, the president of Kikai Labs.