J T wrote:
I've been trying to figure out some sort of machine to shake rattle
can spray paint. I've been able to figure out a few that would probably
work, but a bit more Rube Goldeberg than I would like.

However, even better, I think. A sabre saw, or Sawzall, to provide
the motion. Probably have to make a frame of some sort, attached to an
old blade, to hold a can in, possibly just with rubber bands - don't
want to make it too complicated.

Haven't tried this yet, but plan to. Possibly using a timer, so
can just set it to 2-3 minutes, and leave it. I can't think of any
reason something like this wouldn't work. Would sure beat shaking the
cans by hand.

Here is "The Correct Way to Shake a Spray Paint Can."

http://www.woodzone.com/tips/shaking_spray_paint_cans.htm

Looks like you'll need an orbital motor of some kind. :-)