How to meet people in Bangkok when everyone seems to leave after a few months?

Meeting people here is not the hard part. Keeping them is, because the foreign population turns over constantly and a lot of new friendships expire on somebody's flight date. The pattern that seems to survive it is repeated contact rather than introductions. We have written up why the churn happens and what tends to work against it: https://meetlocale.com/guides/how-to-make-friends-in-bangkok What we cannot document is which specific things worked. Which class, gym, club or volunteering slot produced a friendship that outlasted your first month?