That is precisely how it works, yes! You can also use rice, but I'm given to understand that rice can burn people, while feed corn doesn't have that issue. I have no idea if beans work. The heating/cooling packs can come in various different sizes and shapes, but the ones I'm planning on making are going to be in the range of 6"x21"/15cm x 54cm or 18"x10.5"/46cm x 27cm (a "fat quarter yard" folded in half). The long ones will be divided into four "pockets" of corn, and the larger ones into six pockets. This is mostly because the first one I got was divided into pockets, but it does also mean I can use less corn when making them, and they're easier to roll up to fit in the microwave than if I just... fill it all the way up.
They're very useful! Pretty comfortable, in addition to holding heat or cold reasonably well, and, as I've just discovered, really cheap to make 😉 They do have a faint "popcorn" smell when you heat them up, but I find that's part of the charm. I like to use them to heat up my bed before I get under the covers, or leave them to warm up my car seat while I'm scraping frost off the windows in winter mornings. I haven't used them for cooling just yet, but that's mostly because freezer room is at a major premium in my house, and I kinda forgot they had that function until quite recently 😂
Oh, and cotton flannel is the fabric I usually see used for them; possibly because it feels warmer and/or can kinda... fluff the chilliness? Anyway, they're great! I've been wanting a second one for absolute ages (one for each knee while I'm driving!), but I haven't had any luck ordering them, and the person who made the first one I got is no longer with us. So I guess that means it's my turn!
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They're very useful! Pretty comfortable, in addition to holding heat or cold reasonably well, and, as I've just discovered, really cheap to make 😉 They do have a faint "popcorn" smell when you heat them up, but I find that's part of the charm. I like to use them to heat up my bed before I get under the covers, or leave them to warm up my car seat while I'm scraping frost off the windows in winter mornings. I haven't used them for cooling just yet, but that's mostly because freezer room is at a major premium in my house, and I kinda forgot they had that function until quite recently 😂
Oh, and cotton flannel is the fabric I usually see used for them; possibly because it feels warmer and/or can kinda... fluff the chilliness? Anyway, they're great! I've been wanting a second one for absolute ages (one for each knee while I'm driving!), but I haven't had any luck ordering them, and the person who made the first one I got is no longer with us. So I guess that means it's my turn!