>>937291065
Helium canisters for balloons. No idea where to get them, how much you would need, and how expensive they are. But from what I've seen, you make some very easy setups with large plastic bags.

Another method is using your car if you have one. Hook the car exhaust to the inside of the car with some piping, seal off the exists best you can, start the car and fall asleep in the back. You won't wake up again