Gummy erasers and eraser shields are good enough for old-school industrial designers. Laypeople using regular erasers, however, may grow frustrated with how ordinary erasers wear into a pebble shape, making precision erasing impossible.

Japanese designer Hideo Kanbara has thought of this, and come up with an eraser called the Kadokeshi, which always presents a sharp corner:

Kanbara's design was selected for the MoMA's "Humble Masterpieces" exhibit back in 2004.

You might reason that it gets tricky to hold onto once it shrinks. Well, manufacturer Kokuyo also makes this "stick" version that comes with a dispensing handle:

Image: Masayuki Takabatake

Image: Masayuki Takabatake

I learned about the Kadokeshi over at Masayuki Takabatake's B-LABO site.