What are some alternatives?
When comparing VR Sketch and Kodon, you can also consider the following products
Tilt Brush by Google - Paint in spaces around you with Virtual Reality
A-Painter - Paint in VR in your Browser
MasterpieceVR - Powerful VR sculpting & painting tool
Oculus Medium - Sculpt, model and paint in virtual reality on a 3D canvas.
SprayPrinter - Convert digital designs into wall art from your smartphone
Quill by Story Studio - Paint in virtual reality on an infinitely scalable canvas