SpudFiles

I’m planning a DIY project to build an automatic marble shooter using only recycled materials like plastic bottles, PVC pipes, and old springs—no electricity or compressed air. Has anyone tried something like this before? Any tips for designing a safe and reliable feeding mechanism and adjusting the shooting force so it works consistently for both small and medium marbles?

Interesting project! You could try a spring-loaded lever system using tension from cut plastic bottles or rubber bands for force adjustment.
Have you considered using a gravity-fed rotating drum (from a plastic bottle) with notches to prevent multiple marbles from jamming?