My wife hangs all kinds of stuff from the side of our wire shelf, using whatever make-shift hook she can find. So i designed a couple to fit the side of the wire shelf. There is a flat, then, there is a curved which I think will be stronger. The wire shelf is one like you get at Home Depot or Lowes. the sides are just over an inch (1.1") or about 28mm. Similar to this shelf:

Wire Shelf

I printed mine in ABS.