@legendary rider: I've considered fabricating a tensioner from delrin or other suitable plastic with a metal backer attached with screws or rivets like what you're thinking. However, I think that the different expansion coefficients of the materials might create some issues with stress on either the plastic or screws. When subjected to vibration or pressure from the chain, it could cause the plastic to fracture. Before this is used in an engine, it might be appropriate to test the configuration under similar heat and loading conditions.