Bend the metal strapping in the shape shown in the picture. The spot at the bottom of the can has been bent to increase rigidity and help hold the can in place. You'll drill a hole which is larger than the gas flow outlet, but smaller than the black nozzle pressing piece. I carefully cut apart the large trigger head off the can of air to get the piece that presses down on the stem. I would recommend hot gluing it to end of the can to increase durablity.
Version 2.0 will be a plastic spacer with an interior diameter slightly smaller than the nozzle and an outer diameter that can be strongly mounted through the metal strapping. It should be much more durable and reliable.
Next assemble and align the hole with the nozzle. Slide the hose clamp over the end with the rope attached and down around the bottle. CAREFULLY!!!!! tighten the clamp to hold the strapping in place, but DO NOT compress the can itself as that would be VERY risky. If you're concerned with grip you can slip some rubber inside the hose clamp.
To mount the entire apparatus into the costume, you can screw the strapping or Gorilla Glue the strapping into place.
IMPORTANT: You have to mount it angled so the top is pointing down so that the liquid shoots out and not just air.
SAFETY: As a consequence, if there is inhibited flow, cryo cold liquid can drip out and possibly burn you. Don't mount right next to your eye or other pieces of skin.
To do a quick change setup, you can attach the hose clamp to the strapping, leave it slightly loose and slide the bottle through it . This helps in a contest where you may want to blow a LOT of smoke/steam, but not have to take things off to "recharge".
For the string setup, it will depend on your costume. You could employ a straight pull, a pully, or guide tubing to get the angle just right. You can add tubing, but you can only go with short lengths and minimal bends as it will condense and not give a good cloud effect.
Lighting: A game changer is to add a small LED flashlight to the mounting setup (second hose clamp). When you shoot the cloud at night you'll get an effect almost identical to the crazy beam coming from the unicorn. You can also change color.
If you use this design, please post a link in the comments!!!