Had a Zeb Star Wars Mashers and used his head, arms and legs along with a Bishop sans those pairs. Green Stuff to fill in and create some of the clothing.
On a side note, I'm going to confess to not being up on the Rebels series and therefore note followed or heard of any discussions on him. So this thought I had, may have been floated by someone before. Is it just me or does Zeb like a little like the McQuarrie artwork of Chewbacca?