Micron makes them.
It's like using the photoshop brush tool only without ctrl+z!
No actually they're awesome. I need one in every color, especially blue, red and purple (I just have black right now.) I finally got it out last night and spent the next two hours drawing horses.
I haven't drawn horses in months. It was an amazing mid-finals moment of release.
Also a confession: sometimes I sneak onto this account and search for horse names from my stable. I get really happy when I see people using offspring of theirs. Then I sneak away again, and my day is that much better.