I just whack off a section that looks good based on the graphics on the bag. I turn it inside out and sew the bottom closed. I sew a piece of twill tape in the seam to reinforce it. I fold the top edge down and use another piece of twill tape to face the raw edge. Then sew on the poly webbing for handles. Sometimes I sew triangles at the bottom corners to make a flat bottom. I have also used a piece of duct tape over the bottom seam to reinforce it some more. I have never lined mine, but have seen it done. Oh, you can actually press the bag a bit if you are very careful. Cool iron and a press cloth. I'll see if I have a picture around here