Fun little short
I think the one suggestion I could give you is that in the beginning when the pencil is erasing, it would be cool if it had a cast shadow also. It just kinda appears and erases stuff but it has no shadow so its kind of disconcerting when the pencil starts drawing and the shadow is back. So I would either have it appear on both or not at all.
I liked the characters and the whole punching himself bit at the beginning was a humorous solution.