Most of what Federation ships use for construction is Duranium for the hull.
I would surmise that these materials would have to be reproducible as a synthetic substance in abundance.
Dilithium crystals might be the only thing needed that cannot be synthesized... but we don't know for sure whether the Federation was able to create synthetic dilithium crystals by the 24th century.
We do know they also need Deuterium for 'fuel' (which really doesn't make any sense - but the stuff is basically 'everywhere' and it would be rather idiotic that a culture as advanced as the Federation wouldn't be able to synthesize it artificially).
The Feds can employ a number of highly sophisticated technology in the late 24th century even during war-times.
Actually in the DS9 episode Penumbra it was stated that the Galamites were supplying the Federation with Duranium. It would seem the war was so bad that the Federation had to rely on allies to provide them with raw materials.