I am making some slings, and have not been happy with the selection of fabric at my local fabric stores. They seem to offer a lot of synthetic stuff, or the 100% cotton calicos they offer are just a bit too "weak" for a sling. Anyone know of a good place to buy fabrics online, and what I should look for in terms of a sling fabric? I want the fabric to be as light as possible, but still strong. Thank you!