From the campaign:
Here are some sketches for four of the User Submissions that we've received so far. If you have selected a User Submission tier, feel free to email us at email@example.com with details (which Marta reads). If you mentioned your submission in the comments, please send them to firstname.lastname@example.org, since it's too many things to keep track of.
Also, if you're interested in a User Submission that doesn't line up with a currently unlocked pack, just email us and we'll discuss the details.