> ...I can't think of any project entirely focused on building from scratch and kick-starting the industrial motor of modern civilization.

That's a national defense-scale ambition, and it is akin to asking, "what are the minimal constraints to reproduce X tech tree with Y years steady state sustainability?" You're basically asking what it takes to establish an independent human colony without support from home.

The Long Now project is addressing a small sliver of the question by looking into what it takes to long-term sustainably perform some acts of information storage and dissemination.

Folks into preparedness kick the can on the problem, assuming some certain level of infrastructure remains to pick over the remains of to rebuild/restart. The ones who can hold out for 10-20 years independently before rebooting over the remains of civilization are considered extremely well-funded and hardcore, but their generations-spanning outlook is pretty dim. Even the primitive skills-oriented teams have no good solution to how to pass those skills onto future generations, other than bigger communities to spread the information loss risk, and these teams are typically too small (a couple dozen at most) to look into that direction for a solution.

But no one to my knowledge is working on the overall tech tree problem. Our entire civilization runs as a proprietary binary blob, with no reproducibility in the event of a DR incident.

Even if you "just" "settle" for "only" a 1940-era tech base, we're probably looking at a minimum 45.3M people to participate. The 1939 "Census of Manufactures" identified 453 separate industry classifications. Guesstimate 100,000 absolute minimum number of people per classification, and that's going to be a lowball number of active participants. Toss in dependents and families, plus ancillary support and we're probably around 60M minimum? US 1939 population was 130.9M, so I'm guesstimating we can't get away with less than 50% to create a sustainable "reaction", 66M in round numbers. I'd probably peg it around 75-80% for robustness, and take all the information encoding technology we have today to increase the density of knowledge and know-how per worker to increase the robustness and recovery speed simultaneously instead of decreasing the number of people in the enterprise. Even with the benefit of perfect 20/20 hindsight of what worked and what did not in the past 80 years, it will likely still be a long slog.

To give you a concrete glimpse into what "from scratch" entails, just look at the Gingery book series of what it takes to go from charcoal and scrap metal to a basic machine shop. Getting charcoal from bio-matter is a pretty straightforward task, if you've practiced it before. If you want to extend "scratch" to pulling ore and refining it, now the effort level gets to pretty large scales. Then coming up with refractory-grade clay. Don't forget how to feed yourself in the meantime. The complexity scale just to get beyond subsistence level from scratch is quite harrowing.

Civilization is the most complex artifact the human species has created to date. Re-creating it from scratch would be a pretty tall order that no one has yet to offer even a proof of concept upon. I do welcome discussion on how to solve this with alternatives.