I always liked doing work in pencil - and using a pencil with big eraser. Those add-on erasers were always handy since the original equipment eraser always ran out before the pencil. For the big jobs the rectangle soy based gum was the best for avoiding paper tears and unsightly smudge marks.
Ellen has been collecting Japanese erasers. I remember some odd shaped add-ons in my day - but nothing compared to this sophistication. These erasers dismantle into many "puzzle" pieces. Obviously for collecting and admiring and not for the function of making lead disappear.
"Everyone makes mistakes - That's why there is an eraser on every pencil" --- Japanese Proverb