I've gone with 5cm long, but thin and spindly on two track units for the minoris, so maybe 7-8cm with a slight increase in width.
The ordiantus are basically a huge weapon + targeting system + power plant + void shields strapped on the back of some sort of haulage vehicle. I guess with every battle it survives it might become more militarized until it's basically a super-duper heavy tank, but to start with it's a kludge of the Machine God.
Real life the biggest sort of transporters we have are tank haulers, so imagine if you welded two of these together, one carrying the powerplant, the front one carrying the weapon and a little cab down in front! They're going to be slightly narrower than a typical tank because the transporters are designed for road (or rail). I'm not so sure what to use for the corvus assault pods version yet.
