Need help with school project

Hello,

I would like to ask for some advice regarding a school project for my final exams. I would like to build a small conveyor-based sorting machine that sorts objects by color, but I'm not really sure how to make it work.

The main issue is that I am not sure how to implement it. Even my teacher is not certain how such a project could be designed and built.

Could you please tell me what components I would need for such a project and approximately how much it would cost? I should be able to get a PLC on my own.

Thank you very much for your help.