I pinned the top of each chamber closed as I filled them up so that they wouldn't spill out. Next I tucked the edges under and sewed them closed. (This seemed like the most challenging part of the whole project). When I sewed my divider lines I stopped 1/2" from the top. I think it would have been easier to tuck in the edges if I would have given myself 3/4". Next time I'll try that. These can be made with different fillings. Some people use flax seed or quinoa or barley. I think when I make more I may experiment with different fillings to see which retains the heat the longest. I heated my cozy up for 3 mins about 1/2 hr. ago and it is still quite warm.