A while back I finished building the paint shaker as per the video I posted above.
I didn't have a camera then so I didn't capture the process but I'll post pictures now of the finished paint shaker.
Instead of having an on/off switch + a speed controller like in the video I combined them in a single unit.
I turned the 3D printed bottle holder upside down as that's the way I have always shaken paint bottles by hand- I found that the air pocket and bubbles rising to the top of the bottle releases the paint that settled on the bottom.
It took about one weekend in total to build (over several weekends while I waited for parts)- I added an extra heavy base so it wouldn't jump around like in the video.
It has worked flawlessly - the only problem is remembering to put the bottle in about 30 seconds to 1 minute before I need to use it.

