>>14356956You don't at the beginning of any potential Mars colony. ISRU is a serious consideration for a colony perhaps 50-100 years after it's initial founding. Before then the plurality of raw metals and manufactured components will arrive in bulk shipments via regular fleets of cargo ships.
Remember that ISRU here on Earth requires an industrial base which took 2-300 years to build, things like mining require prospecting, exploratory drilling, and then the buildup of a large mining operation all of which can take years even in our (compared to Mars) friendly environment. On top of that industry demands a huge amount of electrical power, Mars will have to build it's power grid up from zero and that will also take decades.
What Mars has to offer at the surface which can easily be accessed is basalt, carbon and water ice, and limited solar power. Things like metal alloys and complex circuits will take a long time to establish the industries for, and things like complex organic chemistry may never be possible since Mars has essentially zero biosphere to concentrate organic compounds, polymers, hydrocarbons, etc.
