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For modern folks that aren't in a warzone, these heat-shrink self-soldering connectors are super useful for automotive or household work: https://www.amazon.ca/Kuject-Connectors-Waterproof-Electrical-Automotive/dp/B073RMRCC3 https://www.amazon.ca/Kuject-Connectors-Waterproof-Electrica... You do need to provide external heat though.