try 10 gauge steel wire. its thick and rigid but you can still bend it by hand, though normal wire cutters will have some trouble cutting it. ive recently picked up making chainmail and i bought some 8in bolt cutters, their like 10 bucks.
if you want some thats still strong but that you can cut with normal wire cutters, get 14 gauge wire. you can usually get 100ft for like 7 bucks.