With too much gold burning a pocket in a character I've decided to look at random one use items.
Lo and behold, the Feather Token - Chest. At first blush it seems like a one use 10 Bulk limit bag of holding. But, unlike a bag of holding it doesn't have text saying that things placed in the chest don't affect its overall bulk. Which is weird, but okay. So I can store things in this chest, but it'll weigh an awful lot.
Even stranger, the chest turns into a key "taking its contents with it", so now you have a 10 bulk key floating around. Someone should drop it on a big bads head and see what happens.
Bulk and weight are not the same thing. You could, for instance, fill the whole things with feathers.
As a general rule, an item that weighs 5 to 10 pounds is 1 Bulk, an item weighing less than a few ounces is negligible, and anything in between is light. Particularly awkward or unwieldy items might have higher Bulk values. For example, a 10-foot pole isn’t heavy, but its length makes it difficult for you to move while you have one on your person, so its Bulk is 1. Items made for larger or smaller creatures have greater or lesser Bulk, as described in Items and Sizes.
They are highly correlated. Just think about a backpack. It says you ignore the first 2 bulk, but the rest is still in there and affects your carry limit as usual.