3D systems engineer and owner of Grass Roots Engineering blog Jim Smith managed to make the first 3D printed kayak despite the normal limitations for 3D printing. 3D printing can be very difficult when it comes to large-scale projects.
Jim built the boat in pieces rather than one whole kayak; 28 parts were assembled to make a fully functional boat. The parts were made out of ABS plastic. The spaces were filled with silicone caulk to guarantee water tightness.
The whole project took 1,012.65 hours and Jim even had to build his own 3D printer to accommodate the large-scale project.
This just goes to prove -- if you set your mind to do something, you can do it, if you keep trying.