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You have a project that needs: 1000 hours of Data Collection, 50 hours of development time, etc.
But, you have a chicken and egg problem. If enough people put in the time, it would be successful, but only after a certain threshold of effort is met. No one wants to "go first" and put the risk in.
I feel like this could be a solution. If enough people pledge time (maybe with backups) the project could be a success.
Simple example might be an ebook with different chapters written but different authors.