Designing a 3D printed plane is not an easy task! This video outlines a few of the hurdles introduced by 3D printing techniques.
Please note that this technique of printing is mostly a proof of concept, obviously there are better techniques such as having holes in the outer skin and covering with a thin film. However I wanted to try a fully (100%) 3D printed wing.
If you fly a drone or RC plane then you will really want to build or buy one of these devices because it can make a huge difference to the safety of your flying