I tried making hooks myself from some mild-steel cross supports off an old metal shelf; they were little more than sheet metal, and did not hold their shape very well under heavy load. The metal braces Meoates1 suggests would probably work much better, and I think I'll try that next. I've also got some leather from an old couch to make nicer bags out of this time (my first were fabric tote bags from a conference, only slightly more rugged than reusable grocery bags.)