So, I lied just a bit with my time line. Sorry! So, here goes....
The 40mm and 60mm "Tech Factory" bases from Secret Weapon.
After washing the bases, they got a good basecoat of black.
They were then given a second coat of deep grey.
Followed by a top-coat of Shadow Grey.
When the completed basecoat was dry, I gave them an initial wash of Vallejo Black Ink.
When the wash was dry, the initial base colors for the details were applied. I used "Golden Yellow" for the warning tracks, gun grey for the stamped metal and "Fenris Grey" for the lighter metal.
I then continued with the rest of the detailing, adding metallics for pipes and rivets, filling in the warning tracks with black, dry-brushing "Old Brass" on the mesh areas. The stamped metal got alternating patterns of "Fenris Grey" and "Space Wolf Grey" to marked the raised areas.
The detailing was finished by highlighting the edges, coloring the wires, and adding the initial scratch marks.
The next step was edging the scratches to make them sit better on the base.
The next step was adding the oil stains. I started by painting the major spill areas with water. (This step is a bit tedious, as you have to do it one-by-one, so the water doesn't dry to fast.) With the water still wet, I touched a loaded brush (with a mix of Vallejo Black Ink and Devlan Mud) to the water spots. I let the ink bleed with the water and left it to dry however it wanted to.
To finish them off, I added the actual 'oil' - Realistic water mixed with black ink.
As can be seen below, I used the same process for the 60mm base:
And that's the large "Tech Factory" bases painted and ready for use with minis.