Create a button for Copper Cable next to the ones for Red/Green Cable.

[Kroetnaton]

We currently have a button for red and green cables in the bottom row of buttons, but not copper cables.
Copper cables now work the same way as red or green cables, they don't need any actual items, they are only used for power connections the way the others are for circuits, but copper cables can only be used by hitting Alt+C, a fact which can (as far as I can tell) only be found in the key bind settings and nowhere else.
A separate button for the copper cables would help
1. bring awareness (especially for newer players) to this mechanic being in the game at all.
2. give easier access to it. Since it's only used in specific situations players might not always remeber the short cut.
3. incentivise usage of a very powerful but at the moment very hidden mechanic.

[AileTheAlien]

There is a button for copper cables. Maybe it's disabled by default? See screenshot.