Can't help you with a dry rub shaker container. I've been looking for something too. i see these big metal shakers in vids but I don't know where to find them. They would have to have some decent sized holes to let all the goodies pass.
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I found
this after posting and ordered one. I'll try it an report back
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As for longer term storage, I might be doing it all wrong; but I keep my rub in heavy duty double lock ziploc bags in the spare reefer. It contains brown sugar, of course, and I find that the flexible bags make it easy to break up any lumps that form. Lumps aren't generally a problem if I'm careful to remove as much air as possible. I haven't resorted to vacuum sealing yet but wouldn't hesitate to do so.
You guys who vacuum seal the canning jars - how do you do that? My little sealer does bags and has a tube but I don't know how I'd pull a vacuum in a jar.