There's already a number of designs uploaded! Here's my favorites:

The repeat on this one is awesome...

I like the kid friendly colors here -- great for a nursery?

This one has a lot of potential for large curtains -- I'd pair it with stained concreate floors and a relatively strong industrial Victorian vibe.
Need help getting started? Wait for my next post for a site full of inspiration!
Designs are due by 2/15.
Thanks to Projektmanagerin for pointing this out.