This is mathematical! The apparel designers at Bif Bang Pow! are releasing a new "Traveling Jake" tin tote gift set, available through Entertainment Earth. You can check out the details here! The tin tote is a recreation of Finn’s backpack with Jake traveling inside. The gift set also includes a stainless steel "Jake" container and a hardbound Lumpy Space Princess journal. It makes a great gift, and a great container for carrying around your Super Porp. The listed price is $36.99.
This gift set is a convention exclusive that will be available at San Diego Comic Con. The Entertainment Earth booth #2343 will start selling them on July 8th, 2015. It's a limited edition set and there are only 1500, so they will probably sell out fast. If you're not going to be at SDCC, you can still preorder them online. However, supplies are limited, so it is not guaranteed that you will get a copy if they sell too many at comic con.