ok guys i fiddled with these things off and on for two weeks and i think i found the easiest way to do it. I tried foam, tight fitting foam, loose fitting foam, weasel ball in the front, weasel ball in the back. different positions of weasel ball so it rotated differently, i tried everything!
here is what i found works the best
with a magnum sized decoy, big enough for the weasel ball to roll around in...
1. cut out three sides of the top flap, leave one attached and just bend it back to get the weasel ball in and out, easier that hinges, and conceals better than Velcro
A. drill a pilot hole with a drill and then use a box cutter to do the cutting, a drimmel tool leaves too big of a line and
is harder to conceal, the razor blade leaves a very thin line that's easy to hide
2. put your weasel ball inside a tube sock and double it over so there is a good amount of fabric to insulate noise and provide traction for the weasel ball rather that plastic just spinning on plastic, like a dog slipping on wooden floors when it tries to run
3. stuff the dang thing in the decoy and let 'er go
this is totally random motion and it works the best out of everything i've tried
no messy foam, no Velcro, no hinges,
simple, cheap, easy motion in the spread Enjoy Gents