They match Polybolos Beta almost perfectly. Makes me glad I took good notes a couple years ago when this project started!
Still need to do the freehand chapter insignia and finish the banner (saving those 'till all the infantry are complete), but I've gone ahead and completed the unit designations according to the original plan...
Polybolos Alpha | Ahnighito's Zigouilliers | Polybolos Beta
The idea behind these particular units is that all three are part of a larger whole. While the Zigouilliers are Veterans of the Long War, both Polybolos units are fresher recruits to the Iron Warriors cause, relegated to trench-line defense under Captain Ahnighito's command. Thus the Zigouilliers' full chevron is split on Alpha and Beta's pauldrons, each getting the left and right halves of the commanding unit's markings respectively.
I've also been making pretty good progress on the remaining infantry in the force...
Iron Palatine Gibeon w/ Breaching Squad Aerugo
...getting each unit up to step 6 in the process. While it's been easiest to do the initial layers simultaneously up to this point, I'll be splitting 'em off from here on out. The plan is to finish one unit this month while devoting a significant portion of my hobby time to the projects I'm committed to for Adepticon 2014.
More updates as time and progress warrant!