Why make your own avy airbag when there are many options to choose from?
Admittedly, a manufactured airbag system is going to be better than what I show on this page. But for those of us who are poor, or have limited to access to airbag supplies this is an option.
If you think about it, those of us too poor for ski passes are the ones out in the backcountry the most and we're also too poor to afford an airbag. A BCA Float is $500 for the bag then you have to buy the canister for another $175, which is still way cheaper than the $1000+ for an ABS North Face system, which runs on nitrogen which limits your ability to refill it. Lame.
On this site I lay out a design which will work with any backpack so you can carry what you want, and cost a little over $100 dollars. It's convenient and airline safe, as long as you discharge the air canister and weighs in at about four pounds, but could be even lighter. It runs on compressed air which you can breathe in a complete burial and also make a larger space.