I've been wanting to knit my plastic bags into a sturdier reusable bag for a while.  I found some great directions for making plarn here: http://hakucho.blogspot.com/2007/06/how-to-turn-plastic-bags-into-yarn.html   I was wondering what kinds of bags are the best to use.  I have a ton from my grocery store that I'm going to try, but they're the clearish variety that rips easily.  I also have some…