All the 3-levels? Major spoilers follow. Do not read this unless you want full solutions:
3.1: Push left statue left into hole. Walk back to start. Push remaining statue onto gold sigil. Undo to left of gold statue. Push two spaces right of the hole. Retrieve silver and push into bottom hole. Walk into bottom left nook. Push gold down into hallway. Undo into nook.
3.2: Walk into bottom nook. Walk into top nook. Walk left of silver sigil. Push statue onto silver sigil, then right into hole. Step into top nook. Push gold statue left under top nook. Undo into nook. Push statue down. Undo until you're standing left of a restored gold statue. Push statue under top nook. Undo into nook. Push down. Undo into left nook.
3.3: Push left statue down to the bottom. Undo until the silver sigil reactivates. Push second statue down to fill topmost hole. Push gold statue into left hole. Undo silver out of hole.
3.4: Push statue into hole. Walk onto hole. Use a "first level" undo to retrieve the statue. Turn statue red, and place between holes. Now the undo magic (this is seriously brilliant - kudos to the developer) - use the "second level" undo to undo every step you made until you're standing on the hole.
3.5: (finally figured this one out) Walk into the bottom nook. Walk to the sigil. Walk into the nook again. Walk back to the sigil. Walk down two spaces. Walk under the leftmost hole. Push the nearest statue down. Undo to get left of statue. Push statue onto sigil, and continue into the hole. Push gold statue left. Undo until you're below the statue. Push statue up to turn it silver, and move it into the leftmost hole. Push gold statue into the bottom hallway. After that it's all undoing until you get into the right position to push the gold statues around.