Water a few drops at a time with a marble in the pot and shake the heck out of it.
Glass marble preferred.
Does not work when you have already added Future Floor Finish to the paint pot as a flow medium because the FFF won\'t reconstitute.
Don\'t ask....
The marble shouldn\'t break the paint pot and should move around well enough in the old screw-off pot to help speed up the process of mixing while pulverizing the semi-hard paint.
Just add about 3~4 drops of water as you go to get it to the right consistency and you won\'t over thin it.
If you fear the lid leaks, then put some masking tape around it to help hold the water from getting all over the place.
Suggest making the marble spin around the pot rather than from top to bottom for best mixing.