The coolest 3d printers are the SLA ones that use a laser to cure layers of resin - proper scifi shit

You can also do it buy extruding a line of plastic and building up layers that way - it's not as neat, but you can make really structural clicky things (eg: like those click buckles you get on rucksacks etc) out of actual plastic. Which is pretty amazing.
And the same principle works for chocolate....
