Where to find specifications for pressure for an Iron Lung

Iron lungs require industrial infrastructure to construct. They much resist the pressure of atmosphere over a large surface. I think they've been made obsolete by other tech.

But you need to isolate the pressure around the body from the neck down. For such an enclosure you can use modern materials with high tensile strength like fiberglass but you need to mold them in a sealed manner on a large scale. Very impractical to do in a garage without experience and tools for laying fiberglass matting, or welding in the case of steel or aluminum, which are too heavy to be practical in a home I think