Water-cooled stirling engine

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So... this is a water-cooled external combustion engine made with spray paint cans, steel and aluminum wires, copper tubes, high-temperature silicone sealing, screws, etc. It's an evolution of my last engine, but it's not perfect. There are things to improve in the next project:
the power piston is still made of rubber, which sucks;
the displacer piston is too small and heavy;
the copper curve (cylinder) is in an inconvenient place;
cooling is insufficient, so I can't heat with lamps, only with candles.