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You must understand that when you add a layer of insulation to the outside of a mechanical device that the heat will build up inside. You need to consider just how fast the typist user will be hitting the keys and factor that energy into your calculations vis-a-vis the melting point of the various metals and possible eye damage to the operator with incident radiation. But I'm sure you have already taken these possibilities into consideration.
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Come, come, now. Isn't it safe to assume that any self-respecting touch typist with decent skills would have added a liquid-cooling kit prior to burying their typewriter under a layer of papier-mâché?
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Neil Diamond's song "Forever In Blue Jeans" playing in the back-ground...
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