The current Blacktip hull was designed to be printed in sections. The thinking was that a multi-part design could have the pieces printed in parallel, greatly speeding up the time to create a custom hull. As a result, the current hull design consists of 12 large sections. A large format, heavily modified, delta 3D printer was used for printing most of the hull pieces.
[Update: We found that while parallelizing printing does speed up the printing process, there is a point of diminishing return with the problems caused by, and workload generated by, having a hull composed from a large number of parts. The result is that our future designs will use as few individual pieces as possible, and trying not to have any hatch or external opening span multiple pieces. Large hulls will still require multiple printers unless truly massive custom printers are constructed, but any time saved on printing is lost elsewhere.]
For a sense of scale – here is the hull after a little over 6 solid weeks of round the clock printing. The two nose pieces were printed on a small Cartesian 3D printer, while the rest of the hull was printing on our custom large delta.
If that sounds like a long time – the box of failed prints made to get here contains another 5-6 weeks worth of printing and learning. Embarrassingly it took two failures caused by brownouts 5-7 days into a print to realize that a UPS was mandatory during hull printing. Most of the rest of the failures/time were spent dialing in supports.
[Update: To anyone printing hulls – save yourself a lot of pain and use a slicing program that allows you to manually specify where you want supports. Especially in regions where supports are going to be used in cavities that need to be cleaned later.]