This is Warmaster Nice’s (from the epic40k.co.uk forums) fantastic Epic scale Feral Ork Airship.
Based on the Forgeworld Warmaster Dwarf Airship he has done a fantastic conversion and paintjob.
EDIT: Though it looks like it was converted from a Forgeworld Airship, according to Warmaster Nice though inspired by the said airship was in fact scratch-built, which is amazing, he has done a fantastic modelling and paintjob.