Okay. So, we start with the standard Lexan lid...

I started out with some silver to look like metal and some browns to look like rust

Pretty much have most of the inside of the lid rough painted with a brush, then started corroding the metal with a Dremel.

Here's the first 'orange' rust coat airbrushed on the outside.

Rust comes in many colors so it's all about getting different shades for different scratches.

I had some other plans for this lid, that's why the pickup bed is cut out. It gets repaired later.

Splattered some clear coat just to give a really rough surface prior to body color then another rust color over that. This is a major step to achieve the blistered rusted look.

Picked out the most common colors of the era and went with turquoise and light blue.

It's an old truck so some of the body panels and parts have been replaced through the years.

Some of the paint is lighter than other places to account for some fade through the years. If ONLY it had been parked INSIDE the barn.

Now it starts getting some more rust on the outside.

Starting to get heavy handed with brushed on paints

Here's where the clear splatter between coats pays off. Given a day or two to dry completely, a light wet sanding with 320 grit gives you this effect.