you use high quality muslin, if you buy the wide stuff (90" or 108") you can just get 2 separate pieces. (or of course what ever size you want to work with. lay a piece out, and draw 'channeles' across it...9"-12" apart is a good size, then turn and cross them again making squares of your chosen size. (you may want to make a little one to get the hang of this) put the two pieces of fabric together with your marked side facing in. stitch around 3 sides with 1/2" seam; turn right side out (markings now outside) press edges and stitch again around it with the first seam enclosed in the new seam (this helps keep the feathers from working out of the seam) now, this depends on how big you are working with....if it's big you only want to stitch your channels a little way at a time. if it's not too long, start at the seamed bottom of your (big pillowcase) at the center line, stitch up that channel. then working from one side stitch the channels so you have tubes. pour into each channel your clean feathers, so they are even across and as full as you want them, stitch the cross line, enclosing them... add more, stitch across...when you get to the top double fold the top and double stitch...this then can be used as your (batting) in a quilt :)