Make a plywood or clear lexan top for your kettle and make a hole in the center about 1/2" dia.
Get some quality tight grained wood like a cabinet grade maple and cut 2 paddles that fit the shape of the bottom of your kettle as close as you can.
Attach them on a 1/2" wooden dowel that sticks above the lid you made.
Attach some type of handle or cranking/turning device to your 1/2" dowel.
Crank away.......I doubt you'll be doing it by the "shaking" method.
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HINT: When making your kettle corn..... if you think you might have put in a little too much sugar....... then just add some more!
Seriously though, I find if it's too much sugar added.... it just forms clumps of melted sugar in the bottom of kettle, it doesn't seem to have any adverse effect on the popcorn