Working with 3D models is incredibly hard when you can only see in 2D. I've had this problem working with SketchUp, Blender, and other modeling programs because the perspective doesn't work with me (I'm not talking about orthro). The feature would be incredible for displays, as any display can do it. All the user needs is a pair of red-blue 3D glasses to do this. Also add a slider to ajust the intensity of the 3D. This will make TinkerCAD that much more user-friendly, as the tech works with your eyes, so you can see the 3D model you're working with, in 3D.
3D Anaglyph Mode