Take a piece of copper wire (electricity wire) of approximately 2 mm thick.
Cut it to pieces of 12 mm long. Pinch the ends of the pieces flat in a vice (figure 2).
Now drill a hole of 1 mm in the flat ends.
After that the clevises need to be bend. The easiest way to do this is around a big nail. Use a small combination pliers. Figure 3 shows the endresult.
Source: Voor en door de Visser & Poask Hengelsport