Just a small mod that adds 16 backpacks to the game that can be worn in the chest slot.
It gives you double the inventory space, and can be placed down on the ground as a nice decoration!
Buncha Pics of The Backpacks and The GUI
Q: Can you please let us put backpacks in a Trinkets slot?
A: No. It's a lot of extra effort for a feature I don't feel like implementing. It makes the inventory space free with literally 0 cost to it. If you want that, go install any other backpack mod.
Q: How do I craft a backpack?
A: You can install REI to see recipes for all of them, but this is the format.