Re: J. D. Bernal
See [1] which includes the text of a poster from 1977. It makes a grand prediction:
"It is thought that habitats of this type will be technically feasible towards the end of this century, possibly by the early 1990s. One calculation has indicated that with the level of industrial activity which is contemplated for space by that time, and with the means of transportation by then available, construction of such a habitat could proceed in about two months. Accumulation of the shield would take place over the ensuing two years."
[1] https://space.nss.org/bernal-sphere-space-settlement-detail/