Space to open watch (no UI at ALL yet) M to grab/drop the MakerPen Click and hold to draw with the MakerPen E to erase everything (while holding the MakerPen) Q to activate/deactivate the Manual Erasing (It works like how drawing is done (meaning click and hold to erase) but it erases instead of drawing.) If flying press W to go up and S to go down.
If you see this the fly cheat code is Left Right W W. (Toggle)