Built it 22 years ago, still have it. Plywood cut out to go round over my shoulders, then padded so the edge of the plywood doesn't dig into my shoulders.
The manufactured , professional stalker has an axle from the goon's head straight down to hook up to your own head, maybe a little beanie cap and a chin strap? I was just told this I have never seen one.
The heads are now syncronized!
Flat black painted 1/4 steel rods attached to the goon's wrists make arm movement happen, camoflauged by their dark color against a dark backround as seen at night.
I even made crude lifts to make me a foot higher using threaded steel rods holding two 2 by4's apart with some rubber attached on the ground side for a little traction and sheet metal straps over top of my actual work boots , bolted with 1/4 inch nuts and bolts as tight as I could make it, it was a long hike from my house to the parade and back.
I had to practise walking in these first.
Some of my costumes are more torture devices for the person wearing them.

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"My Insanity is well-respected, until they wiggle free and become a stringer for a tabloid"