The neck armor of a T8 paladin is very tricky. It's a gorget, with a faceplate, and some exagerrated armoring.
I tried a few times, quite unsuccessfully, to make the neck armor. The problem was making it in a way that I could mold/cast, since I'm not a professional caster.
I finally turned to a real blacksmith, Andy, at Pitbull Armory. I told him that I needed an enlarged gorget, with an extra high-collar added around the back that I could mount the cast plates to. What he made me was superb, at a great price, and with fast turnaround. I ended up needing to cut the welds for the collar, and move it up, and tilt it up, for my purposes. But his work was excellent, and I recommend his services for all your metal armoring needs.
The face mask has two 1" blocks of wood on the back, as spacers, then has two downward facing coat hooks. The coat hooks hook down onto the top of the front of the gorget, to keep it up in my face, and pushed outward in front of the shoulder pads. A 1/2" leather strap, with a snap, goes around the back of the gorget, from the faceplate, to hold it in place.