you know, to shake paint jars? I've been using the copper ones but they corrode easily (note to self - copper/patina finish on Klingon models). I'm thinking using buckshot which are lead. Does lead corrode?
I believe in "stirred not shaken" I use long pieces of old sprues..another reason to build big aircraft. I never shake the bottles anymore, too much goop gets on the inside of the lid/on the lip of the jar/can't get the bottle open.
The Robart shakers (at least in the past) had a bad rep for breaking down, especially the battery powered ones. They offer the same basic thing both battery and plug in... I think you can send them to Robart for replacement.
I had good luck with my Badger battery powered mixing wand. It did die after perhaps 5 years heavy use. So I got my $10 worth out of it. I need to get another...
Sadly, I can't take returns of electric items in my shop either. I am not a chain or anything... I just don't know what people do to stuff. If it works and then dies... you have to go to the manufacturer. If it just does not work, then I will exchange it etc.