Great Idea!!! The question for me is would these be shipped out in bottles, does this community have a near landfill waste where you can resources the packaging and modify these in low cost effective ways for them to be able to do different activities like you've explained.
When i saw this this idea, i was like yes that's a strong powerful idea. Allowing the children to tell their own stories in their own way. To move this idea forward could you after try get them to role play their stories? This will create another activity alongside the story stones.