I just wanted to share a little idea that I have been using for a long time now. This is not you average piece of backpacking gear. It's very cheap and is readily available from most all grocery stores.
So what I use is the Reynolds Turkey Size Oven Bags. They come two to a box. At only a half oz. each, and $4.00 they make for a great multi use item.

I use them as a pack liner for my Osprey Hornet 32 and 46. You can use them just as they come or add a piece of self stick Velcro and you have a great very tough 1/2 oz. roll top bag. Use the smaller ones for great stuff sack's, just add Velcro. Use them straight out of the box as a sit pad for around the camp or on the trail. Cut open one side seam and the bottom on two of them and add a piece of tenacious tape to join the two together and you have a very tough 1 oz. ground cloth. I use the ground cloth for camp while I cook or just to lounge around on. They last a long time and are tough for the cost and weight.
Anyway just wanted to share one of the many tricks in my bag.

