Electric Cables? They are hard to make in metal or wood

Electric cables at very easy to make in metal, in fact I'd wager 90%+ at least are made of copper in the whole world.

Electric cables are made from insulation (plastic) and wires (metal). Wires use metal, insulation typically does not, so it's NOT easy to make a whole cable out of metal.

Have you heard of insulation?

Silicon ?

Do you mean silicon or silicone? The former isn't a very good candidate for flexible cable insulation. The later is a form of plastic.

If I say humans are made of polyester you wouldn't correct me? You usually meet them wearing insulation too.

About the only kind of fully plastic-free cable I know of (other then historical examples) is bare MICC aka "pyro", which are copper tube sheaths filled with magnesium oxide powder and the wires in the middle. It's used especially in fireproof installations.

A huge pain to install as it's so stiff and needs special tools and fittings to keep it from absorbing water from the air. It has a large bend radius, and it only good for fixed installation as it will crack open if you bend it a few times. And it's nearly £1000 for 100m. So it's not very popular these days.

Plastic really is an annoyingly wonderous category of material when you consider the flexibility, insulation, mechanical, thermal and chemical resistance it can have (and the price)!