To become a close group, there are inevitable phases any group has to go through: The Orientation phase,  the Conflict phase, the Integration phase and the Execution phase.

Comment:Do you want to build close groups, teams at your meetings or conferences? Be aware of these for phases. Make sure you prepare to manage at least a few conflicts. Do you want to avoid the conflict phase? Than don't put groups together for a long period of time like a few days. Be aware you will not build real integrated teams in that way.