A very big 3D printer

My friends at Metrix Create: Space have just completed the first major step in yet another very cool project.  They have converted an old CNC router table into a FDM 3D printer.
They are using a industrial shredder to convert old milk jugs into HDPE chips.  They are then fed into a hopper and a drill and auger bit push them into a custom extruder heater body.

While most RepRap sized printers use a 0.5mm nozzle this printer is using a 6mm nozzle.  This size is needed to have reasonable print speeds.  They initially plan to print a boat (for a milk carton derby?) and are looking for feedback on what they should print next.

I think 3D scans of people printed life size could be very cool.  Maybe this would be an interesting thing to print...