Since this seems like a common question from people, I figured I would do my part to shine a bit of light on how I went about making these vaults.

The main resource for this, is the documentation for how to export structures with the Vanilla Expanded Framework: https://github.com/Vanilla-Expanded/VanillaExpandedFramework/wiki/Exporting-buildings

The rest is pretty much just building the structure, and placing the things such as steel, medicine etc. Once done, you export the structure, and copy-paste it into the appropriate .xml - for this, you can just take a look at how this mod is made by opening this mods folder, that's how I figured it out, by just looking at how the VFEA mod has it set up, and compared it with other mods that add vaults too.

There are a couple mods that are either essential or very useful, so consider the following:

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2023507013
- Required

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2654846754
- Required

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3009409392&searchtext=palette
- Let's you have multiple "dev palettes" profiles, which means you wont have to juggle adding and removing developer commands for spawning in stuff like steel, survival meals, and anything else you can't build through the architect menu. The issue it addresses, is that if you add too many commands, the dev palette goes outside the screen, so there is technically a practical limit to how many commands you can have at once.

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2804579809&searchtext=build
- Extremely useful, as it allows you to make non-buildable stuff buildable, and easily accessible in the architect menu. Once done with your maps, you can either disable the mod, and/or make a backup of the config options file where all your adjustments are saved. Note that you need to restart the game for your changes to take effect. I would also highly recommend you to make a simple custom helper mod (Designation.xml), where you just define some custom architect designations to put these buildables in, otherwise it gets cluttered.

Here is an example of what I made for myself:

<?xml version="1.0" encoding="UTF-8"?>
<Defs>
<DesignationCategoryDef>
<defName>DRA_Vaults</defName>
<label>Vaults</label>
<order>-50</order>
<specialDesignatorClasses>
<li>Designator_Cancel</li>
<li>Designator_Deconstruct</li>
</specialDesignatorClasses>
</DesignationCategoryDef>
</Defs>

As an example, you can make all the "ancient" Ideology and VFEA stuff buildable, the same goes for Vehicle Expanded wrecks. Without this, you need to use the dev palette, where you can only place stuff without a preview, and you also have to use a rotate dev command AFTER it is placed, which is very limiting and hard to work with. If you make stuff buildable, you can simply rotate it like you would any other buildable stuff. The costs do not matter, as you will just be enabling godmode to build stuff for free.

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2258431182&searchtext=whats+that+mod
- With this, you can easily figure out which mod a structure or item comes from, which is useful because you want to limit how many different mods you use in your vault designs. You can make custom architect menus like explained before, if you have a lot of non-buildable stuff from a mod you want to use.

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1713367505&searchtext=rimsaves
- I use it to have a folder that contains an empty sand-filled "template" map save, as well as a separate save for each of my vault designs. You can also use it to create save backups along the way, by duplicating the saves, and moving them to a separate folder.

Here is an in-game example of what my setup looks like: https://i.imgur.com/dSMmbHG.png - I recommend using the "Destroy" dev command, rather than deconstruct with the architect menu, as deconstruction may leave resources on the ground, where "destroy" just removes it entirely. Clear area (rect) is the same, just for an area. When building your roof, I suggest you enable the roof-view widget in the bottom right (looks like a house). Be mindful of the flooring/terrain you use, as in some instances, you might be using a modded variant of a visually similar terrain or floor from the base game. An example for me was the "BrokenAsphalt", which I can also place as a floor tile, but they are not the same. The rest is mainly just spawning resources, weapons etc. You don't have to worry about the actual quality or amount in a stackable item, as those get randomized when the vault is generated.

Anything else is up to you. If you want to make a vault that has Vehicle Expanded stuff, then you also load that mod. If you want to add Dubs Bad Hygiene stuff, you add that one too. Just keep in mind, that the more mods you use for a single vault design, the more empty it will be, if the player is missing those mods. So either use those extra items sparingly, or make the most influential mods required in the "KCSG.StructureLayoutDef". I would recommend you to stick to one major mod influence at a time though, but that is up to you.

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2102143149&searchtext=props+and+decor
- Just a note on this one, cause I had it enabled, and it just adds a lot of clutter, which oftentimes are non-functional versions of e.g. all the "ancient" Ideology stuff, which makes adding the right stuff to be buildable a bit more of a hassle. I would recommend disabling this mod while you are setting up your buildable stuff, then you can always enable it later if you intend to actually use it.