I have been playing in 3d. I measured OEM cam tensioner. This is what I came up to. I still haven't disassembled smaller wheel on tensioner so I am not sure what is the diameter of pin that holds smaller wheel.
Bigger wheel has a hole for HK1312 needle bearing, so it will fit on existing pin(bearing). I designed smaller slider to have longer contact with chain.
For slider I am thinking maybe Polyamide PA6 + MoS material. Thats Polyamide plastic filled with Molybdenum Disulfide. It has
really good characteristics for this kind of applications.
For wheel I think grey cast iron will do(EN-GJL-250) or same Polyamide...
I am willing to open source it.
It would be nice if someone can measure or already have distance between center of crankshaft sprocket and center pf cam sprocket.