Here's a safer alternative. What if you dipped something into a glass of water and it froze around the object?
There's a granulated chemical called sodium acetate. It's an exothermic freezing compound. Well after you boil it into water that is. Exothermic means that it disperses energy when heat is applied. It's the opposite of endothermic, where heat triggers the absorption of energy.
When you boil it into water and keep the water refrigerated it looks like water. Well like unset jello, but closer to water, and stays completely clear. When it is poured into something warmer than itself(room temperature) it will freeze form top to bottom almost instantly. And it safe to touch, and safe to be around. *JUST DON'T DRINK IT*
If you look around online you can probably find some. I hear it's fairly easy to get. When you find a place to buy some make sure it's Sodium Acetate Trihydrate in pure Granular form.
I've used the stuff before and it's really cool. You can trigger the freezing process buy touching the surface, don't dip your finger in though, It froze around mine once. Some times it can act as a skin irritant though, depends on your skin. But dont worry if you finger does get stuck, the ice is hot!
EDIT:
What I failed to mention is that it's a tad bit expensive. This site sells it for the cheapest I've seen. $15 USD for 500g (just over a pound). One site wanted $80 for the same amount.
http://secure.sciencecompany.com/Sodium-Acetate-Trihydrate-500g-P16276C670.aspx
And check out youtube, there should be a video or two on it, just search Sodium Acetate.
Have fun and be chemically safe at all times.
