Direct quote 1997
“The reason why we're going to the trouble of actually modeling them this way, is that the 3D model reveals things to you that are hard to see in 2D. [...] we're building the structures with blocks and then using a CCD (a tiny camera) to peer inside them.”
What it documents
Kojima said in 1997 that almost all the maps he had personally drawn in 2D on graph paper turned out to be useless when converted to 3D, because a 3D model reveals things that are hard to see in 2D; to design the buildings and bases of Metal Gear Solid they were building them with toy blocks and then using a tiny CCD camera to peer inside to detect irregularities, such as a door that should be visible but was obscured by a column.
Source
shmuplations.com; MGS development interview in Famitsu Weekly (1997), unofficial English translation. View source ↗
“All these maps that I'd personally drawn in 2D on graphing paper, almost all of them turned out to be useless. (laughs) [...] Actually, right now we're trying to use toy blocks to model the buildings and bases.”