When I first made this army, it was entirely footslogging. But, two nights before my first game, someone told me I had to have more mobility so I had to get razorbacks or rhinos. But how to make them fit my Mechanicus GrimDarkGothick theme?
I was broke at the time, so rooted about in my bits box and saw what came out... Luckily I found some shockingly painted & rather beaten up an old-school rhino and predator. With the tracks removed and stuck onto a few Cities of Death bits, I created my mobile shrines to the Machine God (rapidly nick-named "The Razorbricks"). The gun-servitors are made from Catachans with Ork heavy weapons. They're magnetic, so I can easily pull them off and stick on a hatch to make them into Rhinos.
The paintjob is, as always for me, rather basic and tabletop-quality: black spray; Boltgun Metal drybrush; details picked out in various reds, whites/greys & bronze; Badab Black wash. Does the job, quick & easy!