This is how I painted up the Adeptus Mechanicus crates from the Kill Team Arena box set.
I primed these crates with Rustoleum Red Matt Multi-Surface Primer Spray paint, to make getting a solid basecoat easier.
Basecoat of Gory Red , the equivalent of Khorne Red.
Recess shade any areas that will not be bordered by metallic trim. I used a 1:1 mix of Wyldwood and Contrast Medium , but any dark brown would do. On these crates it was only the arches and the border of the Mechanicim symbol that needed doing.
Add a chunky edge highlight of Mephiston Red to the top of the arches. These will be the only exposed edges, so we can ignore everywhere else.
Edge highlight the same areas, this time with a fine line of Evil Sunz Scarlet .
Highlight these edges again, this time be selective, using small lines of Wild Rider Red
Basecoat all of the trim with Leadbelcher .
Wash all of the metal with Guilliman Flesh . Make sure a little goes down over the edges to add some contrast in the recesses.
Edge highlight all of the trim with a thin line of Sycorax Bronze . Just run you brush along the edge wherever possible.
Add spot highlights of Stormhost Silver to corners and prominent points.
Adeptus Mechanicus Symbol
Basecoat all white parts with Corax White .
Basecoat the other half with Abaddon Black .
Wash the white area with Apothecary White and Contrast Medium , mixed 1:1.
Where additional shading is needed on the white, I recommend glazing in some thinned Thunderhawk Blue . If there are any particularly deep recesses, pop some into there too.
Now carefully edge highlight the white with a fine line of Ulthuan Grey .
Pop dots of Dead White or you pure white of choice onto corners and on pronounced curved edges where light would hit the white areas.
Add chunky highlights of Dark Reaper to raised areas of the black.
Add fine highlights of Thunderhawk Blue to the edge of the previous highlights.
Add scratches and patches of damage with Rhinox Hide .
Underline these brow. Patches with Wild Rider Red .