The last steps are to make a blade out of cardboard and aluminum foil (do NOT use sheet metal, as it may actually decapitate someone!).
Then poke a hole in the weight center of the top (where it balances), put the fishing line through, and tie a knot so it doesn’t back out. Do not tie it directly to the blade, or the fishing line will not spin freely, and it will tangle.
Add your hook or suction cup a little over twice the length of the spinning arm above the ground.
Run the line from the blade through the hook. Mount the motor where you want it, and turn the motor so the arm faces directly away from the hook.
Extend the line from the blade so that the blade is a few inches below the hook, then run it to the arm and either tie it off, glue it, or tape it. This should leave you with the blade all the way up, and the arm at its farthest.
Remove the arm from the motor and apply power. Wait for it to finish its brief high-speed cycle, and stop it. Then replace the arm so that the blade is all the way in the down position.
If nothing catches on the line, then apply power and you should have a working guillotine.