What are some alternatives?
When comparing Tilt Brush by Google and A-Painter, you can also consider the following products
Snap Art - Snap's augmented reality platform
MasterpieceVR - Powerful VR sculpting & painting tool
SprayPrinter - Convert digital designs into wall art from your smartphone
Oculus Medium - Sculpt, model and paint in virtual reality on a 3D canvas.
VR Sketch - A tool for designers to draw inside virtual reality
Blocks by Google - Easily create 3D objects in VR