3 or more shells with 50% or more infill
This is an easy print and works great in PLA... not tested in ABS.
Do not use 'any' automated support otherwise your Z-Rex jaws / mouth may not move. Print with at least 3 shells and 50% or more infill to make the jaws / mouth as springy as possible.
Train your Z-REX not to bite things it shoudn't!