How about this? It uses --max-parallel to limit build to one process per 3 GB of memory:
https://salsa.debian.org/knielsen-guest/openscad/commit/3c64461f18762bbc2a1eebefe3c5f8880726791a This should prevent builds failing due to out-of-memory on small machines, and still allow most machines to benefit from the great speedup that parallel build provides. - Kristian.
