I treat The Streets I Know like my personal shopper. Almost anything Melanie picks out, I love -- including this Askida hat, which she posted about here. I bought it.
Unfortunately the hat was slightly too big despite its claims of fitting an "average sized adult head" and all . Big enough that at the slightest strain of wind, it would go flying off my head. (That wide brim catches some good wind.) So I needed to figure out how to size it. Several online searches yielded that self-adhesive weather-proofing foam tape was my best bet. Which seemed, at best, strange -- and at worst, wrong. So I reached out to the vendor for ideas and, lo and behold, weather-proofing foam tape it is! (It looks like there is legit hat-sizing foam that looks just like weather-proofing tape.)
This was really easy, cost all of $5 and took so little time that I wish I'd done it sooner. You can see video instructions here -- although all you really need to know is pull the sweatband of your hat out so you can stick the foam strips under it. Cut strips of the foam to fit under the sweatband and adhere them to the inside of your hat. Then fold your sweatband back over the foam when you're done. (You don't need to re-adhere it to the hat's sides.)
^ offending hat and self-adhesive weather-stripping foam ^
^ sweatband pulled back, black foam applied ^
Not to be like "Long live the internet!" or anything but it's super great that it takes so little time to figure out how to fix things so they're still usable. If you look for them, it really prevents so much waste. *fist pump*