I'm looking to make a new object with completely custom functionality, and would rather build it up from scratch rather than trying to untangle a mess of pre-built functionality that I don't need 70% of.

Unfortunately i'm struggling a bit due to 90% of tutorials being "Here's how to recolor an object", and documentation on the core functionalities seemingly being lost to time. I'll document it myself if I have to.

The current issue i'm struggling to solve myself is that adding resources like new CRES and GMDC nodes don't seem to save their changes. Their names get stuck as [Resource Node] and [Geometric Data Container]. When I add and edit new blocks and commit, those blocks then completely delete themselves once I leave click away from the resource no matter what I do.

What am I missing that makes these resources work? I tried adding an MMAT node that points to the CRES, but it can't locate it in the scenegrapher, probably because I can't change its name at all.

The issue is that pretty much all the resources are linked to each other in some or another way, so the easiest is to start with something that's close enough to what you want, and then go from there, deleting resources you don't need (and making sure you don't delete the wrong ones).

For meshes, when you extract them, it's usually best to extract them "all in one" from the same item, since the GMDC/GMND/CRES/SHPE are interconnected. Otherwise you could end up with a broken CRES resource, or pretty much anything else broken.

The TXMT/TXTR/MMAT are more forgiving, and can be extracted from any file, but they still need to be properly named and linked up to show properly for your file.
These tutorials (along with the linked one by IgnorantBliss) shows some of the connections:
https://hugelunatic.com/adding-recorable-subsets/ (this one in particular)
https://hugelunatic.com/making-objects-recolorable/

A full-on 2how everything is put together" is too much to type out here, though. If you poke around in an object file, you can find most of the how and what on your own. It's also a good idea to follow some of the more advanced tutorials that shows how to edit stuff you normally wouldn't for a plain object/object conversion - adding subsets (how to add texture resources properly).

In a lot of cases if you want to make "something else", you need most of the same resources as you would get by cloning something that's roughly similar to it - but you can edit most of the resources to fit your project, and you can also swap out resources (but need to make sure everything is linked up and named properly).

Hugelunatic has some useful tutorials here (sorted by level at the top)
https://hugelunatic.com/category/home/ts2-basic/

And there's an archive of various tutorials here, which could potentially come in handy:
https://ts2tutorialdatabase.tumblr.com

I know that's the "easiest" way, but if I can't build even one thing from scratch, I won't have a full understanding of the "whats and whys", and i'll continue struggling later when I work on my more ambitious mod projects.

I'll take a look through the tutorials you sent, though im not sure if they answer exactly what im looking for. I'll mess around with them later today.

Depends on how "from scratch" you're trying to do this.

If you mean you're starting with just an empty resource in SimPE and - I don't know? Building up resources from scratch?... Good luck. It's likely going to be a struggle, and most likely you're just making a lot of trouble for yourself, and not gain all that much.

If you're starting with extracted resources you want to combine, then that's pretty much what people do when they clone items. Items can be cloned, or the resources can be extracted directly from the game files.

If you're on a beginner level, maybe look into how to make default replacement objects (possibly clothes, too). For some of those you have to build the file somewhat from scratch (with extracted + edited + relinked resources).

Most resources can be edited to fit your needs. It's less work to edit one that's got at least some of what you need, than one that's completely empty. You learn quickly how and what you can edit, even if you don't do everything from scratch. If you poke around enough in the files, you'll start to see how they're put together. It does help if you can put together a working object via cloning, and edit various things successfully.

It also helps to be comfortable enough with creating to problemsolve your own files, since you're going to need a lot of that when you're building up your own files.

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Since I've got absolutely no idea what kind of item you want to make, or what level you're on (beginner/advanced - have you made animated objects? BHAVs? Etc.), here are some more advanced tutorials that could come in handy:

Some (older but still relevant) tutorials by Echo (full list)
https://modthesims.info/wiki.php?ti...torials_by_Echo

A look into the scenegraph, and how to understand the different resources:
https://modthesims.info/wiki.php?ti..._the_Scenegraph

If you want to make a new skeleton for an object, with new animations:
https://modthesims.info/showthread.php?p=1877533

BHAVs + interactions
https://modthesims.info/showthread.php?t=222531
https://modthesims.info/member/showthread.php?t=142907

To answer some quick questions, yes I do mean from an empty resource to a functional object.
While I know it's not "optimal", I also think it's the best way to learn all the functionalities of SimPE rather than taking something already made, breaking it, and not understanding why it's broken because I never learned the core mechanics of the program.
Once I have a full grasp on what SimPE can do, i'll start taking different routes with a better understanding of how to organize and modify them. Trial by fire and all that.

In terms of modding and game development, i've made mods for other games, and work in the industry professionally as an animator, but i'm a complete beginner to SimPE. The learning process here is a bit more frustrating than other software due to the documentation and community being pretty scattered, but if I can spend a year learning and reverse-engineering UnrealScript, I can take whatever time is needed to figure out SimPE.

If I could just figure what makes mesh-related resources start functioning, I might actually start getting somewhere. It seems like everything that gets put in the 0x1C050000 group has some outside requirement for them to work, else they don't save any blocks or changes made to them.

If you're completely new to SimPE/creating, I still suggest making something the usual way, just to familiarize yourself with the process and what's needed in a file, how to make it show up ingame, and how to fix common issues. You don't need to create a big thing from scratch or anything - but the whole "make it show up" is going to be key if you want to go the way you want.

There's absolutely no point in building up a file from scratch and then have it not work or misbehave because you skipped a basic tutorial (I can think of several potential things that can happen).

If you clone a file, you get all the resources in their properly linked form. It's easier to have a file and read it backwards to find all the references and see how it's all connected (it's a rabbit hole with lots of tunnels), than starting with a blank slate and try to make anything make sense, especially if you don't have experience with the files.

I know how to recolor a texture or change a file in an existing clone, that's basic file replacement.

This entire time i've been taking clones of existing objects, breaking them, fixing them, and copying their details into clean resources.

The only question i'm trying to ask is why is it that I can extract a CRES from a table clone into a completely empty package, delete all of it, commit, and then rebuild all of it manually, and it works completely fine.
But if I manually create a CRES and put in all that exact same info, it doesn't work at all and disappears the second I click away from it.

It's like theres some hidden backend that ONLY existing resources have, and whatever it is, we can't put it on our own resource nodes.
And this ONLY seems to be relevant to CRES, GMDC, GMND, SHPE, TXMT, and TXTR nodes (Ones put into the 0x1C050000 group). All other resource types seem to function fine.
Is it tied to the HexEditor? That's the only thing I can see that's not only different between these things, but unable to be edited.

I don't care if the answer is "nobody knows", I'm putting this question out in the hopes that SOMEBODY understands whats going on behind the scenes with these specific resources. Until then, the solution is just to empty out and extract those specific resources into a library to paste into other packages, if only because it's impossible for them to function otherwise.