Your right, retools by Justin. 
I didn’t say he sculpted the H4 and 5 from ground up, just that he did them.
From what I’m guessing, he retooled them mainly for a larger size. The original masks were quite small. If people think the H18 was small, they would definitely be upset if they just used straight castings of those original masks.
Hell, just take a look at H5, the mask was small as hell, to the point they had to cut a major slit up the back to damn near the top of the head just for it to fit Don Shanks. And even then the thing was glove tight on him.
You can see in the scene when he takes it off for Jamie that he just reaches to the top of his head basically and pulls it apart. Also several behind the scenes shots you can see how drastic it had to be cut.
That would be why I think Justin retooled them, otherwise they would have more angry customers than they did with the H18.
This is the problem with Hollywood movie props, things are not always as they seem lol. You may think wow, mask should fit fine when you have these big dudes wearing them in the movies. Only to find out in real life, they either had tiny heads, or had drastic measures taken so they would fit right.
It’s like actors who look bigger on screen, only in real life they are quite a bit smaller. Same thing applies here. These masks aren’t always as they seem in the films. Tyler Mane might be the only one who actually is as big in real life as he looks on screen. He was a good Myers, but a shame it was in films that are at the bottom of my list.
George Wilbur is about as big as he looks on screen though, but just look how damn tight that H4 mask is on him. Those masks, those original Kirk masks, and even the Don Post “the mask” early ones from the 80’s and even the 90’s, were small masks.
Those Don Post masks were skin tight on me in the early 90’s when I was just a young teenager, let alone adult. And since those were derived from the original Kirk masks, that just goes to show how small those masks were.
So I am glad they are being retooled for a more Universal size. Chris said they originally were going to use the H4 and just laser scan it, but I think after seeing the uproar over the smaller size of the H18, they probably decided it was best if Justin retooled them instead. Just a theory, but it makes sense right?