43.  Use Paint Brush on Plane
  •  Paint on the texture
44.  Save the Stencil to your hard drive and then reload the saved image
  • UV/Image Editor >> Image >> Save Image
  • UV/Image Editor >> Image >> Reload Image
  • After you save the Stencil to your hard drive, make sure you reload the saved Stencil.
  • Reloading the Stencil will let Blender pack it with the rest of loaded images.
45.  Start Game Engine
  • Info menu >>Game >> Start Game Engine
Download Finished blend: