My eldest needed a new sharpener for school. Right from the shop I decorated it in a few minutes with a permanent pen, red. The day after I added the silver drawing. I think a fine correction pen will do a fine job, too. Such a little effort with a 'wow' as a reward.
Addition 25.9.10: M used the sharpener this week and just told me that the red doesn't fully stick. Tip: next time I previously would use a very fine sandpaper (we have '400' ...).