i use the Nancy Zieman method of storage of iron on products...remember that plastic liner that separates the layers on the roll? she takes two whole repeats (or more if you have a lot). Now fold in half lengthwise, making a plastic pocket...put all scraps in and then store right in the pocket that contains the correct instructions for THAT iron-on.... isn't this great? one of her best tips... I have 2 additions... i sew my pocket with 3 or 4 inches extra on the back pc. NOW, fold that into 3 or 4 layers....sew back and forth in the center area...now use hole punch or clip hole in center of reinforced stitching... I use wire cutters to clip the end of a wire hanger...now feed all the pocket holes onto the hanger....when they're all on, stick cork on the end of the hanger both to protect you from injury and to keep the pockets in place and to stabilize the hanger...i poke both clipped sharp ends into the cork...
Two... i keep black, white and taupe woven poly lining in my stash...one end is for cutting, the other end is for interfacing and when i have weird little shapes and small scraps, i put them on the end of the bolt, ironing on in a crazy quilt layout....like puzzle pcs.... then when i need to interface a collar or cuff...i go to that end and cut it with the pattern...90% will already be interfaced and I didn't waste any iron-on product.... the teeny bits between the puzzle pieces are not large enough to effect your garment.