That's tough John, but before you start considering a replacement give this a serious thought.
Laugh if you will chaps, but before you poo poo it, consider the following.
Obviously you require a vari-speed drill, but I presume we all have one.
The soldering iron holder, for that's what it is, was handed down to me by my father, so the thing must be decades old.
It never goes wrong.
They are on eBay at the minute for a fiver. Just remove it from the base, straighten out the prong thingy, fit it in the drill, screw in the paint bottle and away you go!
In the years I have used the 'shaker', the paint bottles have never come adrift except when I unscrew it. You can hold it upside down, sideways, fastish/ slow speed, reverse the drill action. It stays put and mixes the paint perfectly. It really does grip the bottle.
Just get one. You won't be disappointed, and for a fiver(or less) what have you got to loose?
But because it's cheap and looks cob, no matter how much I praise the thing, folks will still laugh. Their loss, not mine.
You people might have one in your workshop already... :thumb2:
Give it a whirl( some pun) and see if I'm not right.
Cheers.
Ron