I typed a lot of stuff, and then deleted it, because it started to dawn on me.
It's not about the bricks.
They're making a form.
Just a gut feel, but from someone who's made a lot of shop jigs, done metal-casting, MacGuyver'd rather a lot of doo-dads in all kinds of materials and methods - they're making a big-ol' thing IN that thing.
NOW look at it and tell me I'm wrong.... (wouldn't be the first time, not even today. :-)
AC