For making your own frequent use binders, these filing clips; in either metal or black & white plastic, can be attached to the binder with double sided tape.
Renz Binding Wires A4 34 Loop 3:1
Presco Binding Wires A4 34 Loops 3:1
Presco Binding Wire Spools - 3:1 Pitch
Renz Binding Wires A4 23 Loop 2:1
Plastic Binding Covers