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Looking to Do Volunteer Construction Work Abroad
(lemmygrad.ml)
Talk about whatever, respecting the rules established by Lemmygrad. Failing to comply with the rules will grant you a few warnings, insisting on breaking them will grant you a beautiful shiny banwall.
A community for comrades to chat and talk about whatever doesn't fit other communities
Habit for humanity maybe, I won't vouch for them or any. In my experience, everything is a free labor exploitative scam. In general, without local custom and work experience, you'll be hindering rather than helping. Teaching is always a gig you can find though.
You can also try workaway.info, but see my previous statement about exploit