Thought I’d share my roughed-up version of the pill bottle shaker: Two bottles taped onto a long 'keyless' jigsaw blade... thus, the Double-Barrel Shaker. Adding the second bottle was actually instrumental in eliminating severe lateral wob-b-b-b-b-b-ble!😖
Note how the bottle tabs allow turning clearance between the lids. And with lids in this upside-down mode, Vallejo paints fit nice and snug inside — no spacer necessary.

I’m even considering a triple-barrel version in the near future!🛠
Cheers!🍺
—mike