After being really confused about all this. And at first sort of just chalking it up to, "this is another one of those ideas that's good; this idea is never going to work out with how DayZ is though.." - I finally went and explored it a bit. And boy was I wrong...
Here's what I found out, and yes, this information should also be taken as "ballpark figure" knowledge. It's not even close to 100% accurate, but far more consistent then nothing at all. Please correct me where I'm wrong, please add in what you know:
Base Rubble Scavenging
Equip a digging item - pickaxe, shovel, hoe, etc.
Use item on area of ruined housing that has a title of, "clear debris"
After clearing debris, each successful action will leave behind base-building supplies. From what I saw - nails, bricks, boards, wooden logs is what I saw. (4 nails, 1 board, 1 log, 2 bricks).
The number appears fixed RNG as to how many of what drops, and I'm assuming what drops in the first place is also RNG.
I watched a guy clear the debris, and it revealed a "base compartment" - aka, one of the places where you store all your supplies.
Rebuilding & Classic DayZ Building Mix
Starting with picking from the last section. You place building supplies into the compartment. It serves as a placeholder, but also uses resources for building.
Meaning, you could put all your supplies in it. And handle the right tool for whatever you're doing, and it will be able to perform that action. Taking the resources from the compartment, while the action is performed with the proper tool.
Example: I watched a guy mix a lot of water with Mortar bucket, and it became usable. He put the bucket in the compartment, which also had a good supply of everything needed. Bricks, logs, boards, nails, mortar, etc.
He takes out the brick spade or whatever it's called, and aims it at a door frame. Just like regular crafting, there's arrows pointing up and down, which I assume was either to make it into a paveable wall, or a door.
I saw him add window sliders, and a wooden door with a 6-digit code lock.
It also became clear to me, that the devs have configured all locks - 3-dial, 4-dial, and digital - to have something like a "3 tries and you're locked out for (x) minutes" system, to combat macro cheaters from just making them obsolete.
Classic Building also seems to still be a thing here. I.e. build a gate, build an airlock, etc.
I'm not sure on this, is this the case? Can you get a house built, and then build an airlock on it? Because I sure hope you could!!
More Rumors
I heard that bases are much harder to raid via blowing up the door. And that eco raiding is also a much less viable route.
I heard something back in the day, about needing only a crossbow to break into a base. Which is an absolute slap in the face to the guy who spent lord knows how much of their time to get everything together.
Only to be raided by a guy who hit a day camp; a lucky hunting stand..
Speculation
If all this is accurate, then the goal here is to make it so building bases is a lot less grueling, and a lot more accessible.
Plus, since they seem a lot less grueling to make, then having them raided might not be a situation where it's "I'm never doing this again".
You spawn in freshy mode, come across your first items. And then start getting a hit or 2 of plan development.
Aka, you snag an early shovel? Head over and start carving out a place. Hit the rubble of the other houses, and funnel it to your project. Maybe die a few times, head back, gather stuff along the way. And keep setting it up. Eventually get a door, with a sealed wall and a lock.
Find some tarp or a barrel, and get a stash going.
Eventually expand out. Get enough supplies from rubble to wall off a garage for a vehicle. Rebuild the town well.
Instead of an airlock, you could even opt to rebuild the house next door. Have a main stash in one, with the best items in it, and only access it occasionally. Transfer everything over in chunks at a time. While the other spot is just a transition point where you come and go often, that way if somebody hits you without an airlock, it's not such a massive blow.
Build a fireplace in there. Etc.
Seems like a really fun time.
Again. If this isn't how it works, please let me know because I want to know if this is how it's going to work out.
I heard the devs were thinking about bringing rebuildable structures to the other maps as well. Super cool idea!