The moon has ideal conditions for solar energy harvesting: no atmosphere, no weather...

Since Project Apollo in the 1970s it is known that all the materials needed for manufacturing photovoltaic cells are present in lunar rocks and dust. Not saying it is an easy engineering feat, but the raw materials are there.

Large sun focusing mirrors might be sufficient

That sweet Helium 3 nuclear fusion :) . Oh, wait, it would be just wasteful to use aneutronic fusion to smelt metals on the moon. You could probably sell the Helium 3 back on Earth and just use regular nuclear fusion to do that.

you dont even need a smelter/forger if you want to build a massive space colony at the L1 lagrange point (which the moon elevator would pass through). Just pack the raw lunar regolith into prefab plastic sheeting similar. this is similar in concept to inflatable space habitats with the added benefit of radiation protection and thermal insulation.

https://en.wikipedia.org/wiki/Inflatable_space_habitat

The Sun.