Very important question. What do I need to 3D Print Chocolate? Are there parts that work with certain printers?
3D printing chocolate can be considered “experimental” territory. Look here: http://richrap.blogspot.co.uk/2012/04/universal-paste-extruder-ceramic-food.html for more info. That particular paste extruder will work on most repraps.
Cool idea @Tara_Tiger_Brown - While I don’t have anything substantive to add, I do know that chocolate would present some interesting challenges, and probably awesome outcomes, for a 3D printer setup.
(1) For one, chocolate has an electrorheological response, meaning that high electric fields would cause local, temporary gelling. See for example: http://www.nytimes.com/1996/09/24/science/chocolate-the-stuff-of-shock-absorbers.html
(2) This probably also means that molten chocolate is a non-Newtonian fluid. That could have implications for pumping: pump too hard, and the fluid will fight back.
(3) Chocolate also needs to be “tempered” - as I’m sure you are aware - so seeding with the right chocolate phase will be super-important to get a good resulting structure. I know i’m showing more of my nerdy materials science side, but there are plenty of recipes out there that can give you an idea of how hard this’ll be.
Other than that, I’ve got nothing, except a desire to eat whatever you come up with 
My sister likes to melt and mold her own chocolates, I should talk to her about the temperatures involved and such. I wonder if we could make a more traditional extruder (not a syringe-style extruder) for chocolate… Is there any chocolate that comes in long, uniform blocks (without nuts or anything mixed in). If not, I’m sure they could be made with those long, thin silicone ice cube trays designed for making ice to put into narrow-mouth water bottles. It would be cool to build an extruder that could, for example, push a hershey bar through a heated nozzle the same way we push ABS and PLA through one.
Found this on sugar: http://blog.reprap.org/2012/07/on-challenge-of-3d-printing-sugar-for.html
Found this: How to Build a BariCUDA Extruder https://secure.flickr.com/photos/19255751@N00/sets/72157631469935204/
Here’s another extruder targeting chocolate: http://www.thingiverse.com/thing:18017
See also: Unfold ~fab (http://unfoldfab.blogspot.com/)
@Whosa_whatsis , I know that most culinary supply retailers carry garnishing chocolate in slab form. From my past experiences with it I believe that it would be ideal for the concept that you propose, as it has a higher melting point than standard chocolate and is structurally more stable than other types of chocolate. however it isn’t always the tastiest chocolate at times (depends on personal preferences I suppose) and it might be better to formulate a custom chocolate mix with the desired properties.
For the extruder we could use a water pump in a similar setup to what RepRapPro showcased as a cooling system for their extruders, except we use a peltier heater to warm the reservoir, this would keep the chocolate warm without risk of burning or worse, crystallizing it. this could potentially work with ordinary chocolate chips via an auger system, and there is the potential to have little to no vitamins asides from the motor if the channels for the water are printed inside the extruder.
You want a froststruder with heating element as described http://www.thingiverse.com/thing:26343
I didn’t realize that Jordan had released his extruder desigm.
There ya go, nice people do exist
I wonder if you could use a peristaltic pump to pump molten chocolate. How do those chocolate fountains work?
Most chocolate fountains are standard fluid pumps that draw from a heated resevoir that keeps the chocolate molten.
Fountains are a simple vertical screw pump. If you use a fluid pump, you need to keep that warm too. The simplest way seems to be to use a pneumatic system, and just pump the goop out with air. Releasing the pressure stops the flow. I’ll probably do something weird though.
Tara, tell me more.
I have been doing it for years…
@Hans_Fouche what are you using to do it?