Elmers won't work on pink insulation foam as it needs air to dry. Any 2 part epoxy resin will work but may make carving difficult. Be sure not to use polyester resin as it will eat the foam. I've also used liquid nails but it has the same problem as elmers in that the lack of air makes it take forever to dry in the center.
I use Super 77, just spray on both halves let air dry, then attach, just make sure you get it pushed down over the whole area or you will have Air pockets that will give you problems later on.