I doubt this is a good guess, given I'm neither a civil engineer nor a space engineer, but my guess would be it would look like a machine for laying a railway.

It's a Starship-scale project: something like 100 launches, which is only feasible because Starship is targeting such low launch costs.

I don't know (see previous disclaimer) but I wouldn't be surprised if (assuming circumlunar power is even the chosen solution) this is done by sending up an aluminium factory instead and processing regolith.