Hugo Morvan wrote:pitch your idea to local seed swaps that already exist.
This is a super great idea. Reaching out to your local resources might give you an idea. Where I live, the slow food people are a great resource for seed swaps, for exmaple.
In the US, I know many public libraries went through a phase with seed banks/libraries (the ones I know seem to have left it fall to the wayside, but maybe it's case-by-case). I know I would reach out to my public library and organic center (whether that's health food store or some other holistic type thing, UU church, etc) and see what else is out there. The more the merrier.