Using lego and a few custom components a 3D printer for chocolate is possible. I did this project a long time ago so the documentation is incomplete, but hopefully it will inspire someone to rebuild it and fill in the blanks.
Step 1: Make a Chocolate Extruder.
These were my first rough plans for a chocolate extruder. Powdered chocolate into a heated barrel, lego worm screws as the slurry pump through an ejection nozzle.