I have it in my head that a 3d printer could be made out of silicone caulk using an ultrasonic humidifier to supply the water. basically that is it... there is a humidifier constantly covering the print area with mist and an extruder constantly pressing thin layers of silicone together (layers with a bit of water in between them).

maybe silicone diluted with mineral spirits will get better flow characteristics out of a nozzle and better penetration from the water mist? I want to 3d print "soft actuators" but also tough materials like metal.