Spirograph heart (or cat, or kidney shape, or smile)

My son got a heart-shaped spirograph toy in a gift pack at the movies. After leaving the movie theatre, he left his toy at the restaurant and was heartbroken (pun intended). So, I made him a new shape that works with the (smaller cogs of) this thing: http://www.thingiverse.com/thing:252162

I don't expect many makes, but if you're in the market for a (roughly) heart-shaped spirograph, here you go :-)