Creating a sprocket from PCB with encoder?

[shai]

I am building a PnP Machine and would like to create the sprocket for my feeder out of PCB. See attached.
I know that PCB is not the best material for a sprocket, etc, etc. I would like to focus on one thing only - how to create an encoder for this sprocket. I have a few ideas but perhaps someone with more experience can tell me what would work best and if you have better idea to share?

Ideas:
1. Drill holes in sprocket and use optical sensor (self explanatory, but I'm afraid this is not very super accurate for PCB material)
2. Use two springs that will contact with each pad. Simplest way to do it, just the cycle count might not be high as the sprocket/spring could wear out from physical contact/rotation.
3. Use optical encoder that reflects off the pads and make sure the PCB is matte black. (will this work? or will it still reflect off a matte black pcb?)
4. Use a Hall effect or similar sensor and detect the pads. (This one I'm not sure, non-lead-free pads? is that a possibility? Can any sort of SMT pad coating type be detectable with a Hall effect sensor? I think they are cheaper than optical encoders? Suggestions here?
5. Any other ideas on how to get creative with a PCB sprocket to be used as encoder?

[Simon]

Please do not double post. It is very annoying to all as it causes confusion.