A Few yrs back I bought a set of 6 throwers,& Had the same dilemna.I bought some Aluminum flange from Home Depew,It easily cuts with any scissors or shears,& I crafted some sheaths out of it,Using a pair of Pliers to fold over the edges,& Crimp them down,then I used pieces of 1" shrink tubing over this,then finished with lengths of 10-speed innertube.I use these alongside my G.I. Canteen,between the Cup/cover.They are super flat,& Unnoticeable,Until they're needed!