Vortex Paint Shaker: Paint Shaker Now with 200% More Metal

I use small 2 Oz acrylic paint bottles. Sometimes the paint separates.
I needed this to quickly and easily mix them.
I add 2 of the 2mm ball bearings to help speed up the process.
I tried some other designs but I kept breaking them at the point where they attached to the drill.
I really struggled to design the part that goes in the 3/8 drill to be strong enough so I replaced it with a 8mm bolt.
When mixing I use my other hand to keep the assembly as straight as possible but don't hold the bottle tightly.
I use light tension on the bottle so it still spins.
The Bottle holder is unchanged from this version https://www.thingiverse.com/thing:7030146