Yeah, it doesn't really work like that. A few of the parts (idlers, pulleys, spacers) can be printed, but even those are cheaper to buy than to print, and the quality of an injection molded plastic part is still superior to most anything coming off a <$10K 3D printer. You still need the linear guide rails ($$ = better quality = better prints), motion systems and electronics. You can probably build yourself a makerbot style printer for under $1000, and its not too hard, but it is labor intensive to get every aligned to sub 1/32" precision.

I have a makerbot here at the office, when printing PLA it is pretty nice for a $2K machine. We've easily saved that on some parts we've printed vs. manufactured in the conventional way. A printer that can do carbon for $5k and match the strength of aluminum, I'll take two! I do expect the material to be expensive (much worse than buying ink) and the build envelope is small, but for certain prototype parts we CNC machine, this would be a time and cost savings.

I don't expect this to be very useful on our boats, given the limited print area and relatively high price of materials. I am intrigued by the manufacturing possibilities of the technology, and it may become viable for Nacra/Goodall etc. to utilize this in their shops for certain components.