Design a rocket that could be built in place inside one of the four bays of the Vehicle Assembly Building (VAB) at Kennedy Space Center, which is 525 ft (160 m) tall. Utilize additive manufacturing (aka 3D printing) where possible, considering which materials might be able to be used and which ones may have to be brought in already manufactured.
We looked at using 3D printing to make a rocket at KSC.
In short, 3D printing is a great way to make small(ish), complex components such as rocket engines or even cryogenic fuel tanks. It is probably not the way to build a Saturn V equivalent, because most of the rocket structure is easily manufacturable using traditional techniques.
We found that even with light-weight composite fuel tanks and top-of-the-line rocket engines, it's hard to out-compete the Saturn V. Most of the improvements in the past 60 years have come in materials, manufacturing, and electronics -- none of them are enough to overcome the sheer challenge of throwing several million pounds of rocket into space.
However, 3D printing does offer significant cost and lead time gains in comparison to traditional machining. The Rocketdyne engines, for example, come in three pieces and take about 3 months from order to delivery (or so they claim). In comparison, the Rocketdyne F-1 engines for the Saturn V had thousands of precision-machined parts and took about a year to deliver.
It also offers potential gains in tankage. 3D printed composite tanks are lighter and cheaper per unit volume than metallica tanks. The idea of being able to crank out hundreds of nearly identical tanks with little human interference is also appealing -- no complex welding needed!