Rather than craft an entire cab or shell from pure steel/iron, it may make sense to divide the larger part into smaller parts to that only the steel parts of the cab are casted/forged from steel or iron. The other parts could be crafted on an ordinary crafting table from alternative materials, with IR's current machines, or another method entirely.

Some examples:

WINDOW: made from glass or glass panes.

CONTROL_PANEL: Could involve some glass, though it would be mostly metal.

HORN_BRASS/WHISTLE_BRASS/BELL_BRASS: Made from brass only if brass is detected, otherwise made from iron/steel like "normal" parts.

Mostly applicable to passenger cars, may be too complicated:

SEAT_WOOD: made from planks.

SEAT_LEATHER: Made from planks, wool/stuffing (may need oredict here), and leather or leather substitute.

SEAT_CLOTH: Made from planks, wool/stuffing, and some other textile (string, wool, or cloth)?

PANELING: Probably wood.

FLOORING: Wood/carpet?