I decided I wanted a bunch of guys who aren't Astartes, Astra Militarum or Mechanicus. Instead they're private bodyguards, mercenaries or independent Imperial agents. The kind of hard cases who would be hired by noble houses, merchant guilds, Inquisitors and Rogue Traders, to ensure that bumps get smoothed, and lumps get liquidated. The kind of characters that often crop up in Dan Abnett's excellent Inquisitor books (the Eisenhorn trilogy, the Ravenor trilogy, and, at the time of writing, the first part of the Bequin trilogy).
Some of them will be ex-Imperial Guard, some will be gangers or members of criminal cartels, while others may even have undertaken rare martial training at specialist scholams. Doubtless they are all very dangerous in a civilian context, though it's unlikely any would match up to an individual Astartes or Custodes legionary.
As with most of my scratched together conversions the basic models come from a variety of places. There are three that started life as Urban War Triad Retainers with Naginata Pole Arms (a lot of the excellent Urban War range appears to be out of print now and this is the only picture I could find of the original models), three that are basically Games Workshop kit bashes (trying to use up some of the myriad pieces left over from my 'Dredd' style Arbites project), one from Mike McVey's Sedition Wars range and a Grymn Pilot from Kev White's Hasslefree Miniatures.
All those basic miniatures suffered a bit of chopping and/or repositioning, before I got down to the fun part of the job: covering them in extra weapons, packs, armour plates, cables, heads and belts etc.
Did I have any idea what I was trying to achieve? In this case, surprisingly, yes. For a few of these characters I took my inspiration from the video game Destiny. Looking at the images on this Google search of Destiny concept art, the game is very close in tone to WH40K. Could Destiny have originally been inspired by WH40K?
If so, then in my 28mm take on these things, I suppose the circle is now complete.