There's that really iconic shot that Chris captures of Oppenheimer standing in the tower and you see all the components, including this plate that we fabricated, this diamond plate.
There are early forms of armor from ancient Japan, they were made with metal plates stitched together and narrow strips of bronze or iron held together by leather ties.
They just used a hot plate with either a metal plate or a silicon wafer on top, then the oil (they used silicon oil), then a syringe to precisely place a water drop.
They would tell my dad something like, 'This is what we want, and we want it out of one piece of metal so that the coefficients of expansion are all the same.'