I love baking, so I think it would be really cool to make a CNC dough extruder.
I imagine that it would work like a 3 axis CNC milling machine, but instead of a spinning drill bit, there would be a syringe full of dough.
Then you could digitally design and make anything out of dough, such as breads, cookies, etc. It could also potentially be extended to be used for creating frosting and chocolate decorations.
I had heard of a chocolate 3D printer, which works by extruding layers of chocolate. Here is an example from Choc Edge, which makes commercial 3D chocolate printers.
A similar kind of mechanism with a syringe could be used with other paste or dough materials. One challenge in building a CNC dough extruder would be controlling the pressure and speed of the syringe to extrude the exact desired volume and shape. These parameters would have to be controlled to work for a variety of stiffnesses and viscosities.After I decided on the CNC dough extruder as my final project idea, I did a bit of searching and found that someone had built a universal paste extruder and documented it on his blog. He tried a variety of non-edible and edible paste materials, including foods like chocolate, sugar paste, and cake mix.