so i decided to try something new with those huge mattress bags i knew they used to leak on top which i did a knot on top then i was like what if i try to make it look like an actual car airbag and i did and guddamn i love it!

EDIT: as you can see yu can see the knots as well to hold the bag..what i did is inflated a bit then closed it and then i pull its sides till its a bit stiff and do two knots.