Neat demonstration of EDM cutting technology

EDM (electrical discharge machining) cuts through thick plates of steel within +/- 0.0001".

From Core 77:

In the variant of this production method known as wire EDM, the cutting is done with a thin brass wire and the fun combination of electricity and water. Wire EDM is what you use when you want to cut something that's, say, 300mm thick, and made out of a tough-to-machine metal.