Hello, we have this small tool used to loosen/tighten a metal slotted ferrule. The teeth of the tool engage with the slots in the ends of the ferrule and torque is applied to tighten or loosen it. 

When the ferrule is threaded tightly, the metal edges of the slots push through the teeth and the tool fails. We have tried nylon and PLA and the both fail when the ferrule is tight.

What would be a good material for this part so the teeth are strong enough to to avoid this failure? Torque is applied by hand, so it is not a lot, but the teeth are quite small (only about 1mm thick because that is the width of the slot the must fit into). There are so many process/material choices we don’t have any firm idea of what to try… any suggestions welcome!