Artemiy Karpinsky -- AKA: The Mugbearer -- has a number of interesting builds that could be used for MFZ.
Core Instigator is what caught my eye recently.
This one looks pretty neat too. Shame it doesn't have a name.
MFZ 3 Bombard. This one was actually built for Mobile Frame Zero.
Sentry Plus, this is one of a few re-sized Exoforce models. The pilot looks to be 8 plates tall.
Mini Turbo Mech. This is one of the best non-transforming bipedal flying designs I've seen in a while.
While all the designs I've chosen are made in LDD, he does have some others that are in the brick. Check out his Flickr stream.