While I was working on the custom jewelry problems, I saw that there were a bunch of resources for a teen male "surfer" hairdo that isn't actually in the game. Most stuff is there (shape, cres, etc) but there's no property set or 3IDRs and probably binary indices. I thought maybe I could figure it out on my own, but I kept failing massively. I've seen where people've done this before, so I downloaded some of those files, but looking through them only confused me more. Is this sort of thing accomplished in the same way that custom hair is made or is it just a matter of creating new things that point to the stuff that already exists? I can't seem to find any tutorials, even quick and dirty ones. I guess it's 'cause once someone does it, there's not really any need for anyone else to do it, but it seems like it'd be easier than most things, what with most of the work already being done.

I figure someone will already finish this hair within a day or two, and I half-expect it to show up finished in teen style stuff, but I'm really curious about it now. Anyone have any knowledge to impart?

It just occurred to me that some ruins would be a really cool place for a wedding.

Put the arch in front of the monkey shrine, add some soap...

SO TRUE!

Tutorial: Converting Pre-BV Accessories to Jewelry

Part 1: Mesh Overlay XML (XMOL)

Change subtype to 0x00000008
Change category to 0x0000137F
Change bin to one of the following:

0x00000032: Left Earring
0x00000033: Right Earring
0x00000034: Necklace
0x00000035: Left Bracelet
0x00000036: Right Bracelet
0x00000037: Nose Ring
0x00000038: Lip Ring
0x00000039: Eyebrow Ring
0x0000003A: Left Index Finger Ring
0x0000003B: Right Index Finger Ring
0x0000003C: Alternate Right Index Finger Ring
0x0000003D: Left Pinky Ring
0x0000003E: Right Pinky Ring
0x0000003F: Left Thumb Ring
0x00000040: Right Thumb Ring

Add parts (dtUInteger) = 0x00000020
Add outfit (dtUInteger) = 0x00000020

Part 2: 3D ID Referencing File (3IDR)

Find all the 3DIRs with these entries:

UI Data, Text Lists, Collection, and Mesh Overlay XML

Edit the collection field, changing Group to 0x4F184AA9
Change Instance to one of the following:

0xD327EED9: Non-Vacation
0xD327EED8: Tropical
0xD327EED7: Far East
0xD327EED6: Mountain
0xB343967F: Collectible

Part 3: Notes

Non-Vacation jewelry shows up in CAS and is buyable at any jewelry stand, be it in a normal hood or of the vacation destinations, whereas Tropical, Far East, and Mountain are only obtainable in their respective areas. Some jewelry appears to be Collectible-only, but I don't know if NV jewelry can be dug up as well.

I've noticed some odd behavior with custom jewelry. Custom pieces appear to be stackable with some Maxis pieces, despite occupying the same bin. For example, I binned a pair of glasses as a necklace, and both the glasses and the Maxis necklaces could be worn at once. I did the same thing for a number of different bins, and the results seemed to vary.

Another odd behavior is that the custom things seem to get "stuck" under certain circumstances. For example, leaving the "outfit" button defaulted to "all," then equipping a nosering-binned pair of glasses, then clicking the button to "choose by outfit" made it so that the glasses would automatically re-appear under everyday, even if I took them off. I couldn't find a single way to get rid of them that worked everytime. Best bet is to click "choose by outfit" first, and then start adding jewelry.

RE: adding the "parts" and "outfit" fields - Adding these is what makes the jewelry buyable, for a reason I don't understand. If you leave these out, it will only show up in CAS (if NV-flagged). Adding one or the other actually seems to work OK, but to be on the safe side, I'd add both, if only for the sake of sticking to Maxian standards.

Edit: Holy bold tags, Batman!

Got another half answer for you 

I took a look at the Material Definitions in Sims02, and it appears that all the solid-color jewelry pulls from some other pool of textures. They're named things like reflectionsilver_envcube or reflectionkitchengold_envcube, and some of the rings have colors like "jade" and "blue." I took a look through all of the packages that I know to contain txtr files and didn't see anything. I'm not sure if these things are procedural textures or what. Someone else might see the texture name and recognize it immediately, but this is out of my arena here. The reference section of the Material Definition does have the little "<filename> xxxxx-xxxxx-xxxxx-xxxxx" section, so someone who knows what any of it means can probably track it down. I feel like I read about all of this stuff a year ago and what it all means, but I just can't remember.

This jewelry has absolutely stumped me 

I've spent too long looking into this and have reached a dead end, but I've learned some things that hopefully might help you waste less time in your own research.

I started working with the kids' snorkel/mask from Family Fun Stuff. I was hoping I could reap the benefit of the jewelry's nice per-outfit system so the snorkel could be set to only be worn with swimwear. Basically, changing the subtype and bin number (more on that later) seems to be only half of the solution. As it's an accessory for a child, binning it as a nose piercing would put it in the Misc. section of jewelry, which is normally unavailable to children because they didn't get any face piercings. When I went to CAS to test, I found that I could now click on the Misc. section for a child. There was nothing to click on within that section, but clearly the game recognized that there was some Misc. child jewelry somewhere and it just couldn't display it for whatever reason, and I'm thinking it has to do with the way that certain jewelry is only available under certain conditions.

Based on the lists in globalcatbin, it looks to me like there are basically 5 "types" of jewelry: Non-Vacation (i.e. available in CAS and buyable in normal 'hoods), Far East, Mountain, and Tropical. It looks like changing a pre-BV accessory to jewelry defaults it to type 5, None, meaning the piece exists, and is recognized as existing, but isn't actually obtainable. (Note: there may actually be a 6th type, Collectible, that can be gotten from combing for shells, but I didn't look into it enough to see if it contained any unique jewelry, or if it's just more of a subtype) If I'm right about that, then there must be some way to flag an accessory as a particular type, but for the life of me I cannot find it. The XML for a Far East earring is basically the same as a Non-Vacation earring, aside from the stuff that pertains to the materials. Same flags, same subtypes, same bins, same category, and so on. The only other explanation I can think of is that there's something else ruling over all the jewelry and telling it where to be, and I don't like that idea because it would probably make making new jewelry annoying and difficult.

Regarding bin numbers:
It looks like jewelry is a bit pickier about bin numbers than glasses are. When I tried to give the snorkel a bin number different from any of the pre-determined jewelry bin numbers, I no longer had the ability to click on the child's Misc. category, so my guess is that numbers outside the range don't default to Misc., but I don't know if they go somewhere else instead. I tried to test this further by rebinning one of the Maxis noserings, but the behavior was a bit odd. Setting it to a random number made it disappear completely, but so did setting it as an earring, ring, or necklace. Setting it as a lipring, however, had the predictable behavior of making it stackable with other noserings (Incidentally, I just double-checked, and while I was at it binned the snorkel as a ring, which is also unavailable to children. It had the same effect of making the ring category accessible, albeit empty). The point is, I couldn't figure out where out-of-range binned items go because customs don't show up at all, and the Maxis ones apparently don't like to switch categories.

So that's that. I hit a wall. It took forever to keep testing these little things, having to wait for the game to load, then the neighborhood, then CAS. Hopefully that'll give you some idea of what to look for so you don't have to test all those things.

Fake edit: I forgot to mention that I also took a sim to all 3 destinations to make sure the snorkel wasn't defaulting to one of those types. If "Collectible" is its own type, it's possible the jewelry defaulted there, but I'd rather slam my head in a door than try to test that by hand.