At 2015 Comic-Con
http://collider.com/gravity-falls-comic-con-panel-recap/#highlights
Also, next year we'll see a replica of Journal #3 coming to stores! It'll be 256 pages long, and it contains more backstory about how Stan decided to arrive in Gravity Falls as well as additional info never seen or heard in the show.
Are you sick of piles of owls constantly blocking your driveway? Well, then you need Owl Trowel!