Anyone who has ever participated in arts and crafts, and used a hot glue gun already knows how 3D printing works.
Surprisingly a simple hot glue gun operates just like the extruder of a 3D printer.
A hot glue gun uses pressure (applied by the user) to push the solid glue stick through the heating element, making it “hot glue”. The user controls the dispensing of hot glue in the two dimensions of the X&Y planes (thus making it 2D)… the user could use it in the third dimension, but that is just wasteful and beyond the scope of the device.
Before we get in-depth ...