We are doing Adventure Time for Halloween costumes this year (well, umdude and I are undecided. Although, HT can correct that quickly as well).
Glamgeek wants to be Marcelline the Vampire Queen, and since the main bit of the costume is stuff in her wardrobe (gray tank, jeans, cowboy boots that I'm changing from pink to red), it's really about some makeup and assessories. We decided that the Axe Bass would be a good/easy to haul around, and reusable item (I'm totes going to cosplay this one at a con). Umdude had to drive halfway across the Valley for it, so worth it for me. It would have taken me literal days to craft it.
Last year when eldest was Finn, I spent 30 hours (not kidding) hand sewing a felt backpack for his costume. While it turned out super rad, it was a lot of work, AND he didn't even get much of the kind of candy I nick from their treat bags. I'm calling this a win!