Pre alpha demo by Ashok Mathew Kuruvilla is a 3D modelling app with Google Cardboard and a simple hack pointer interface (made with an AR marker and earphones).
It is certainly primitive and doesn’t compare to the far more sophisticated and slick Tiltbrush, yet is impressive to see what can be done with smartphone augmented reality - video embedded below:
Here is another video demonstrating a construction of a 3D scene using primitive shapes:
I have made a major update to the 3D Doodler app to create 3D content in augmented reality space. The new additions include the color picker, more basic shapes, selection tool and VR mode to view the created content in Virtual Reality.