homemade space bags

I don't know about you guys, but I love the usefulness of space bags, but they are so expensive. A while back, I heard this tip on a tv show but kept forgetting to try it. Today, I finally did and it worked just as well as the store bought ones. You take a regular trash bag, the show said the heavy duty black ones but I only had basic white kitchen bags and they worked fine, put your stuff in it, vacuum out the air, and seal it with a rubber band. I found it worked easiest if I put the rubber band around the bag first, and then looped it around until it was tight after vacuuming. I had my bags standing up like they would be in a trash can and they made misshapen cubes. Next time I think I'll try laying them down and see if they come out a little more flat.