Both Robby The Robot and The Lost In Space Robot were both designed by Robert Kinoshita. He also designed Tobor from the 1954 film Tobor the Great. This puts him near the top of the great sci-fi robot designers. Interesting to note, during World War II, Kinoshita and his wife Lillian Matsuyama were interned at the Poston War Relocation Center in Arizona. His art direction credits also include Hawaii Five-O and Kojak. He passed away in 2014 at the age of 100.
Anyone with a 3D printer (and any interest in robot history) should add these to their collection.
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