This bag was my inspiration. Not that mine turned out anything like it. I was going for another grocery-size bag, and I succeeded.
First I cut up one t-shirt into 1 1/14 inch strips using these directions. I grabbed my size P (11.5 mm) hook and started with a 20-stitch chain and then doubled back and did single crochet until I ran out of t-shirt yarn. I had to do 2 stitches in 1 a few times to keep the bottom straight, but I don't remember the exact numbers. Just make it flat. If it curls up into a bowl shape when you're around the corner, you need another stitch or two. If you made a ruffle, you need to take out a stitch or two.
Then I went rummaging through my dad's house and found 7 more shirts, only one of which was colored. I turned 3 of them into yarn. Eventually I got back home and used my rotary cutter, cutting mat and clear plastic gutting guide to make the strips. My hands were happy for the relief from the heavy scissor work.
I did a lap-join (overlapping the ends by about 6" instead of tying them together) and did a row of single crochet with no stitch increases. Then I switched to double crochet for the rest of that shirt and all but the colored and one white shirt. Each (men's size large) shirt only made 1.5 rows, at about 1" per row.
I wanted the colored strip to be a fairly even height and not have a super-obvious beginning and end, so I took it down to single crochet and got 3 rows almost exactly. As luck would have it, I began and ended at the end of the bag, so it's even less obvious. Completely invisible when photographed from the correct side!
I continued with the single crochet but switched to the last white shirt. I did one complete round and then formed the handles. Two inches before the center of one side, I broke away and made a 10-stitch chain. Then I skipped 6 stitches and rejoined the round. I continued on until I got to the same place on the opposite side and did the same thing. After that join, I continued with single crochet until I got to the first handle. Single crochet made it too thick, so I switched to chain stitch on top of the handle. At this point, I was worried, and rightly so, about running out of yarn before I got to the second handle. So I kept up with the chain stitch until I ran out of yarn. I worked the end in and the bag was done.
I'm proud to say that this bag is made of 100% post-consumer recycled material. No "exclusive of decoration" disclaimers necessary. And all the arms and stuff I didn't use here will get used as rags until they fall apart completely. All I have to do is sew in my tag. Click here to buy it now.