Pinch thumb + index, then move your hand. Pinch with both hands and the sheet follows the line between them, so turning your hands turns the picture and pulling apart spreads it. Stretch one spot far enough and the paper gives way onto the layer underneath. Squash it instead and it creases. Cut a scrap free all the way round and it drops out of frame.
C clear · H hide panel · F fullscreen
This uses your camera to track both hands. Nothing leaves your machine.
The hand model is about 8 MB and loads from Google's CDN the first time.