I remember seeing the Armatron mechanical robot arm in our local Radio Shack and immediately put it on my wishlist. The only electronics are the power source — everything else is motors, gears, and rotating drums to achieve articulation of the joints and clamping hand.
This thing felt like an object that was transported from the future and it seeped into my psyche. The typography, colors, and infographics for the control panel were just one more proverbial notch in my path to designing interfaces these many years later.
You can see a video of the Armatron in action on The Old Robots site.