Define build. We currently don't have the physical capacity to fabricate copper wire on the moon but on paper we should be more than able to with modern technol

Define build. We currently don't have the physical capacity to fabricate copper wire on the moon but on paper we should be more than able to with modern technology. It's worth noting though that it probably just isn't worth it to though for just this. Reason for this being 1. that the moon doesn't have copper in any substantial quantity and 2. that the moon only has trace amounts of carbon (required for organic polymer based insulators) and/or nitrogen (required for most if not all inorganic polymer based insulators). Now you don't need a polymer based insulator but more niche/specialty insulators are going to generally be harder to work with and they come with their own various downsides (limited flexibility, brittle, mildly hazardous to humans). With that in mind you could suppose we do the manufacturing on the moon or in orbit and ship the material up the well (assuming this is before asteroid mining takes off) but the density of wiring isn't really all that different from the base materials so it'd still be the same mass you'd have to bring up the well. And wire coils & packs quite well in a cylinder so volume is probably not going to be the constraining factor for launching it into orbit. So at that point you might as well just manufacture on earth and cut to size in orbit/on the moon. Now if you want to expand the definition a bit (from your basic polymer insulated copper wire to just insulated wire in general), then we could actually. We'd need to replace the wire with something actually present in sizeable quantity on the moon. The main two elements are aluminium and silicon. Aluminium is commonly used for cheaper wiring so it'd be viable for many uses. Silicon or silicon based alloys could potentially be used for specialty cases but that's all relatively exotic material work for little gain outside of semiconductor fab level work. So you'd probably want aluminium. Making aluminium for the mined alumina is pretty basic work (we do it all the time industrially on earth) but it requires absurd amounts of energy to make any substantial amount. As for making the insulator, you could make glass or ceramic insulation from silica but it wouldn't be flexible at all and would be brittle. This is probably a nonstarter for any high power energy transfer due to vibration or sudden shocks/jumps in the wire. You could however make mineral insulated metal sheathed cables using magnesium oxide/magnesia (makes up about 10% of the lunar surface). This would probably be the best solution. And other than the conductor (aluminium or copper), it actually isn't all that hard. So yes it's possible but we probably wouldn't do it for even a large project unless we were actively intending on using it for mass manufacturing for other purposes and it'd require quite a bit of industrial capacity on the moon in the first place.