Like some other GW models, the lowly Engineseer is one of those characterful pieces that seems like he should do more, but isn't as great as he could be, somehow. In my AdMech army, I've been using them as filler models for things like Veteran Squads, heroes and other odds and ends (but strangely, I have yet to field an actual Techpriest in an army list, with or without servitors). The two above are stock, of course, but made for a good STC to use for others. Respirator, robes, backpack, servo arm, tools. Off you go.
I'm not sure whether Dark Age is a defunct series or not, but I keep finding their box sets cheap (as in $6 plus shipping) which makes them ideally suited when found. The one on the right donated his head to a terminator conversion, and in return got an old Necron trooper head (look closely) under his green stuff cowl. The right hand one kept his human one, but wears his as a cogitator skull on his belt (which head is the dominant one is anyone's guess). They're adorned with IG and Flagellant belt bits, along with Necromunda pistols, where possible.
You may recognize the fellow on the left as an ancient terminator, the old cobra-backed one that never really fit in with the other models (and as such, never joined my Ultramarines) Not to fear, as he gained an Obliterator power fist and augmetic arm with a Heavy Flamer. A few green stuff robes to complete the image, and you have a nice Praetorian flame trooper, and a hulking one at that.
The Oblit fist came in a bits auction with chunks of another fellow you may recognize. In fact, I like the model so much I'll post a pic of him again:
Ah, Arch-Magos. So full of weapons and options that he's practically unfieldable without special rules (maybe as a Karamazov? Nah, too small..) That's a TL Plasma pistol, a flamer, a power claw, a blade of some kind, a smoothbore cannon of another kind, and some sort ocular mechadendrite. Oh, and a Rogue Trader Dreadnought left arm.
I suppose he'd be better off with Chaos Lord stats or something. Maybe a Tractor Beam (Lash of Slaanesh) but how to explain a TL Plasma pistol? The Tempus Fugitives list does feature a Magos Prime with a full servo harness and conversion beamer. Hmmm...
The forge halls must be built mighty large to accommodate this monster; he's practically a mini-Titan all by himself. Maybe he has a smaller sub-body to relax in and only wears this one when he's out in the field.
The twins with their odd custom weapon-staves. I like the charging poses of these models, although the two-handed staff grip kind of limits conversion possibilities. The servo-backpacks are all made from standard SM packs, with the vents sawed off and replaced by machine bits, including the wicked saws, drills and claws from Necromunda pit gladiator bits sprue. I may look for some Cawdor or Redemptionist gangers the next time I'm fishing for Skitarii.
Female Mechanicum have always been rather interesting, and it's tempting to take them too far and make them look like jumped-up battle sisters. You have to walk a fine line between all the tech and weapons to keep them looking feminine, and as such these two presented more of a challenge than their male counterparts. The one on the left is a Magos Xenologis, as you can no doubt tell from her Eldar shuriken pistol and the rather arcane touches like the hourglass and cannon-axe weapon. Her companion is more along the lines of a Secutor or Skitarii, with a more aggressive pose and that folded-up flamer on her servo-pack. That hammer could probably do some damage, too...
Unlike the other Mechanicum, these two have purity seals on their weapons and gear. Are they plants from the Inquisition, I wonder? All of the Necron artifacts and gear about the forge might be cause for suspicion of Xenos contamination. Come to think of it, those strange conical "servitors" from a few posts ago have been seen ordering other servitors (and techpriests) about, and are devastating in combat. Hmmm....