That said, technology does one thing magic doesn't do: scale
Whaaat? Let's say you got a factory with 3000 workers in 3 shifts and assembly lines and whatnot and I got a 10th level sorceress with Fabricate. We're making MG 42 machineguns. Each one takes 75 man-hours to make in said assembly line and takes up 1/10 of a cubic foot in volume. So the factory can make 318 guns per work day. The sorceror can make 100 guns in one minute with a single casting of Fabricate - and she has 5 spell slots of 10th level for every 8 hours she is in restful calm, such as reading her favorite novel, sunbathing or sleeping. She can thus make 1500 guns per day and work all of 15 minutes.


But wait, this is totally inefficient. Our sorceress doesn't want to spend her whole life making more guns than 5 factories at once. She thus does the following every day for 3 months - the same 3 months your engineers will be building said factory;

1) Resting for 8 hours/day.
2) Lesser Planar Binding 5 outsiders per day, then killing them for the XP and potential treasure.
3) Working 8 hours/day on her Rod of Fabrication.

After 90 days, our sorceress has completed her Rod of Fabrication, which allows its wielder to Fabricate at-will. She now can, in a single hour, fabricate 6000 cubic feet (a thousand tons) of metal goods or 60.000 cubic feet of nonmetal goods, provided she has the skill.


She can literally build a mansion in one hour, or the Empire State Building in a couple of months, on her own.