That´s how I paint steel plates. It´s the way from Adam Wilder and I try to copy it:

A plastic card is the start:



Primer:



First colour:



First rust colour:



Hairspray or something similar:



First colour over the hairspray:



Remove the colour with water:



A seconde colour:



Tools:



I painted some 3d effects with a lighter colour:





Rust colour from Tamiya:



Then I used some oil colur and pigments for the rust:



Heating zoone:



Last effect:



I hope you can use it.

Very interesting, thanks for sharing!