A free program for Android, by Antipixel.

AR Sandbox is a game that allows you to build and sculpt in augmented reality. You will be able to create and view objects and structures in the real world. It is a game that will stimulate your creativity and planning skills. You will be able to play in the real world, as if you were in a sandbox, with all the tools and materials that you need to build and create things.

How to play:

Find a wide, flat, and well-lit place.

The area should be wide and flat, with enough space to allow you to create and play in the sandbox.