Assault Caterpillar Marine
I received from Berlin the MicroArt pieces I needed for my most advanced conversion (untill now).
It is an Iron Hand marines with half body substituted by a caterpillar tractor.
It will be used "counting as" an Assault Bike with Multimelta.
The next step will be to put it on a base large enough to represent the encumbrance of the original model, in order to avoid any problem with the "count as" rule.
The inspiration behind it are the Adeptus Mechanicus Sagitarii. The heavy weapon operatives of the Mars Techguard. I supposed that IH are linked enough to the Adeptus Mechanicus that they could have some Sagitarii too, and have ones in power armour!