John has stated in the General Exit Path discussion thread that there won't be a feature for you to create your own levels. You should go into that thread and read the last ten or so pages.
I mentioned in another thread that I have no plans to include a level editor, for a few reasons. I am all about giving the users the best experience they could possibly ever have. Level editors are fun but users will go out of their way to make terrible levels and I worry it's going to ruin user experience. I am not ready to build both a moderation system and a level editor, which both will take at least an additional 4 weeks to do and would need even more weeks of stress-testing. I've got so much to do with multiplayer, uniplayer, and everything in-between that a level editor is the last thing on my mind at this point.
