Make sure that whatever solution is chosen is an efficient, practical and sustainable technical solution (see parameters)
Make sure that basic legal requirements are taken care of. The working group will have to explore legal options for a toolserver association (or any other legal option that allows a joint governance and financing of the toolserver)
Chapters are governing the toolserver, not the Foundation, not any other external organisation
Single ownership of hardware
Chapters (toolserver association) will own that hardware (no outsourcing, no rental, no lease)
Keep the existing rules of the toolserver: Work on the toolserver has to be beneficial to a Wikimedia or an Open Street Map projects (potential partner projects)
The resulting outcome should provide a strong incentive for chapters to integrate their locally run toolservers in the Toolserver
Solution has to be agreeable at least to Wikimedia Germany
Assumption agreed upon: only participating chapters influence the governance.
Money
Size of community
Number of people (affiliation to a chapter?) who have an account on the server
Proposals:
Buying a share into the organisation. The number of shares determines your influence in this organisation (you get to decide who is on the board etc.). (Stock company) - ex. German Top Level Domain Association. Model to look at.
Membership fee to stay in by every participating chapter. Commitment over several years
Proportional scheme contribution=influence but there needs to be some kind of commitment in the long term (which probably the share model actually solves)