I made a blank map that can be used to create a setting collaboratively. I hereby publish it under the CC0 license, it's the closest I can get to the public domain without breaking any law (or dying). Feel free to share, reuse and remix it as you see fit!
- Blank map (PDF, A3)
- Editable map (SVG, A3)
Here are two examples of completed settings (in French):
- La Vallée d'Efímerillas (PDF, thread)
- L'Isthme des Brumes (PDF, thread)
For best results, I would advise to ask your co-authors to put references in their contribution to elements that have already been established by others. It really ties the setting together.