I make tons of these every year. But I use organic raw buckwheat grouts instead for a filler. I go to our local 'Good Food Store' and buy them in bulk. 25 pounds at a time :) The main reasons I use buckwheat is it holds the heat better, it doesn't smell (and we've used a couple bags for years) and the buckwheat seems to hold the shapes better.
I purchased a 'shawl' this year that was filled with buckwheat, cinammon, nutmeg, vanilla beans, allspice, and nutmeg. You warm it in the microwave and place it across your shoulders and back. The dimensions are approx 24 x 24 inches. There are little pockets of the mixture sewn just like a patchwork quilt and it lays flat across your shoulders. The top layer is 100 % cotton and the backing is flannel. It folds up and you can heat in the microwave for 2 minutes, open it and refold it, then add 2 more minutes in the microwave and it is heaven! My dd and I made up a couple of these and there is approx 5 lbs of buckwheat in them.