how do you dispose of empty or expired fire extinguishers?
Beach. That would be the most fun, especially for when school get's out. Have a Theme Park theme, and go to the theme park.
Considering the fact that a new smoke detector has about 0.28 μg of Am, I'm thinking you might not have too much success with what you want to do. I have two recommendations: 1) Cease your efforts with the Am. 2) Have some ice cream instead.