The first prototypes are produced following a model that the Navy SEALs already use: the SEAL Delivery Vehicle - or "SDV" for short. It has been in use for many years and helps the elite unit to overcome long distances under water. It is equipped with corresponding technology on board to spy on target areas as well as to infiltrate them as much as possible.
A tried and tested model is to be made more efficient. Thanks to 3D printing technology, this is possible. The production, or more precisely the pressure, is to take place at the Oak Ridge National Laboratory (ORNL) in Tennessee. This scientific laboratory belongs to the United States Department of Energy and has already been able to demonstrate some achievements in the field of 3D printing. One of the most prominent products is not only the first functional car, but also a printed Shelby Cobra.
The current SEAL Delivery Vehicles (SDV) cost between 600,000 and 800,000 US dollars depending on the model. Their production alone takes five months. However, 3D printing can significantly reduce costs and production times: now it is possible to produce such a submarine for 60,000 dollars - within a few days. This proof-of-concept has reduced the cost of an SDV by 90 percent. Once again, it is clear how cost-effective the 3D printing technology can be. However, the research continues. By 2019, Oak Ridge and the Navy want to use the first fleets of production.
You can read the rest @
https://deutsche-wirtschafts-nachrichten.de/2017/08/16/us-navy-seals-entdecken-den-3d-druck-fuer-sich/ [translation required]
As a former submariner, I can promise you flat out I would never submerge myself in a vehicle produced by 3-D printing. SEALs may be brave, but submariners are not reckless.
And I would not get into a 3-D printed Shelby Cobra, either.
But if you think either is a good idea, go for it. I'm certain you will enjoy the ride ... while it lasts.