What's what

The Sims offers the player a choice of Child, Fat, Fit and Skinny. I've already expressed my displeasure at this elsewhere, but to repeat: the Fat female mesh is not fat, the Fit female mesh is not fit (the female Fit swimsuit mesh has a narrower waist than the unisex Skinny one) and "Fit" is in any case the wrong name for what should have been Average. Moreover, although the female Fit mesh has the right outrageous proportions for the average anime babe, the male Fit mesh is far too bulky for most male anime characters, and the male Fat mesh is not bulky enough for the few fat characters in anime. Not to mention the fact that anime characters are rarely all the same height.

Because the body type is a three-letter code which is often replaced by a variable, new body types can be made and used in the game. There are a few things to keep in mind, however:

• When a Sim is created, the game fills in the "dress style" strings (swimsuit, pyama etc.) as well as it can, using what's available. But if a necessary mesh can't be found, the game will crash, either when making the Sim or when changing clothes in the game. Therefore, each body type should come with meshes and skins for all dress styles. An optional addition is work outfits; if the game doesn't find the working clothes for a custom body type, the character will go to work in pyama, but I haven't heard this causes crashes.
• Even when custom body files are present for all dress styles, the "buyable" system introduced with Hot Date will pick "Fit" meshes for any non-standard body type, so the strings have to be edited by hand in an IFF editor (see Simple character editing). For child Sims, the right files are selected for Hot Date swimwear and nightwear, but not for winter wear. Once the strings have been corrected, Sims can "buy" outfits of their own body type.
• All "human" animations in the Sims are for either adults or children, and rely on the head and hands being in the same place for all body types. This is especially a problem with taller and shorter meshes, which need altered head heights. There is some wiggle room for heads - putting them higher or lower results in things like party hats and the VR helmet not being placed correctly, but I can live with that - but the hands must stay in the same place, or they may show gaps at the wrist. Width is also a problem with hands, as they may disappear into the widened body. Very fat bodies may need custom hands, which is a problem as the game doesn't allow custom hand meshes. (See below for the hands issue.)
• Due to the game's naming conventions, custom bodies can't use standard skins. For a short explanation of how to rename a standard skin for use with a custom body, see the warpfiles page. Making five copies of exactly the same skin to have it appear on as many body types is a pain, and it takes up a lot of disk space, but if the GameData\Skins directory gets over-full, the skins can be moved to GameData\Textures.
• Sim meshes are highly simplified and the animations very stick-puppet. This gets even worse with short or tall meshes, the reason being that Sims are animated by revolving their joints around fixed points, and the further the joints are removed from their assigned point, the more extreme their movement. As tests in Simpose reveal, tall high-heeled Sims will horribly dislocate their shoulders and break their ankles opening a dresser, and their heads will practically bobble off their necks when they nod. Fortunately, this is not too glaringly visible in the game itself.
• Heads don't automatically adjust themselves to the body mesh height; for taller or shorter meshes, their vertical offset needs to be changed. I usually do this in BodyWarp with a warpfile and save the head to the same mesh name plus a one-letter height indication: B (Big) for tall mesh heads, S (Small) for short mesh heads, V (Very small) for very short mesh heads. For SUM heads, which need to be inflated rather than raised or lowered, I use U, as the S is already taken. Heads aren't sorted by body type, so heads of any height will appear on any mesh; if the Sim appears to have either no neck or a very long one, the head is on the wrong mesh.

A quirk I've noticed when using custom body types under HD and higher: although underwear/swimsuits are now buyable, the pre-HD swimsuit textures are still stored in the Sim files and referred to when a Sim visits non-residential lots. If these old swimsuit textures are not found, the nude textures are stored and used in their place. This means that a GYT character wandered around nude for a while on each visit to Downtown before the game showed the appropriate buyable swimsuit mesh. So swimsuit skins have been taken out of the pre-HD dress sets and have gone into the nude dress sets. So for children (other than SMA) the pre-HD sets now contain only the unused pyama meshes and are obsolete except for installations which have been hacked to allow custom child pyamas, if that is at all possible.

Below is a list of custom body types I've either made or found useful. For the types made by simply warping a standard mesh, I've put up the warpfiles on the Available meshes page.

Standard height

CBL (Child - belly)
Like CCH and CSM, this type was made to differentiate between the characters of "kiddie G-Force", which consisted of two average children, a fat child, a girl with a chest and a thin child smaller than the others. It's more massive than the CHD body, with a slight gut.

CSK (Child - skinny)
This type was made for Jimpei of "Science Ninja Team Gatchaman", who is the right age for a Simkid, but much scrawnier. It's the CHD body thinned down.

CCH (Child - chest)
Who says nine-year-olds can't have chest bumps? I did! This type was the biggest headache, as it required extra vertices to be added to most meshes. It's the standard CHD body with some vertex editing.

ATN (Average - teen)
Slimmed-down versions of Fit bodies, either for anime characters or for teenage Sims whose bodies haven't filled out yet, but who don't qualify as skinny.

SUM (Sumo)
This body type was made by Jerome; it was probably warped directly from the standard Fat defaults, as the Fat-to-SUM warpfile I made produced meshes almost identical to his own. This is an extremely bulky body type which needs expanded heads and special hands.

BBS (Big-breasted)
An experimental body type that is not so much an altered mesh as a standard mesh with an accessory, but as nude CMXs can't be customized from a certain expansion pack onwards, attaching the accessory for all dress styles requires a new body type code. For those anime females so busty that they're visual jokes.

BBS (Big biceps)
The male version of the above, for those male anime characters with ridiculously swelled chests and arms, but relatively thin necks and waists. It was made for a game character who suffers from advanced Tarzan syndrome. This is simply the fit body warped, although originally it was warped from the ATN body, so any parts that haven't been pumped up have been slimmed down.

SMA (Child-sized adult)
Adult bodies shrunk to child size, for ultra-short anime characters. These bodies use the child skeleton, so the Sim is basically a child and needs its age raised to 12 or higher to get an adult voice (although some animations will still use child-voice soundbytes) and child-friendly hacked objects. They use child-size heads (normal child heads or shrunk adult heads). For this body type the Fit body was warped down to ATN and then shrunk, because the decrease in size exaggerated the already ridiculous Fit proportions (especially the female hourglass waist) so the ATN body looked more natural. There are no formal and high fashion dress styles for SMA, because children can't buy or wear these; instead, the files are renamed to show up as normal skins.

Taller (these meshes need raised heads)

BYT (Boy - young teen)
An experimental type, the CHD body stretched into that of a very young teen. The hands stay at the same position, which means the arms are very long. The shoulders can look a bit odd in animation, and because the texture map is that of the standard child body, textures look elongated.

GYT (Girl - young teen)
BYT's female equivalent, using a different body type code to avoid problems when customizing "UC" body meshes. A further development of CCH, this one has a bosom.

ATL (Average - tall)
A stretched Fit body for extremely long characters like Sailor Moon's Queen Beryl. Made a bit longer for compatibility with an extra long Taiki Kou mesh.

ATT (Average teen - tall)
Included for completeness's sake.

FTL (Fat - tall)
Ditto.

STL (Skinny - tall)
Ditto. (Maybe for scary skeletal anime characters?)

Shorter (these meshes need lowered heads)

CSM (Child - small)
This is the CSK body thinned down even more and shrunk a little, for undersized children.

ASH (Average - short)
Warped Fit bodies first made to correspond with a shortened Sailor Moon mesh so her neck wouldn't disappear each time she changed to pyamas; then remade for the short but slightly taller Yaten Kou mesh from the same maker. Only the top half of this body has been shortened, the legs are unchanged.

ATS (Average teen, short)
Included for completeness's sake.

SSH (Skinny - short)
The shortening warp applied to the Skinny meshes, for those shorter thin-as-a-stick anime characters.

FSH (Fat - short)
Included for completeness's sake.

AVS (Average - very short)
The new name for the original ASH warpfile, because I still needed that short Sailor Moon body type.

ATV (Average teen - very short)
Included for completeness.

FVS (Fat - very short)
Ditto.

SVS (Skinny - very short)
Ditto.

Halfway through 2008, I finally decided to outfit male Sims with appendages. This meant I had to redo all male/child custom nude textures and re-FAR them. While I was doing that, I thought I could just as well do something I planned a long time ago: give custom bodies distinctive underwear so I would be able to see through a quick change to underwear what body type they are. So all S100 textures have been slightly recoloured, in the following way: ATN/SMA now have green underwear. For the three length variations on Fat/Fit/Skn/Atn, the taller form has lightened underwear, the two shorter versions, progressively darkened underwear. For the child forms, CBL has green swimsuits, CSK peacock-blue, CSM violet and CCH red. MABBS is black. Since FABBS, SUM and YT already have clearly different bodies, their textures have not been changed.

The hands issue:

The hands of a Sim, like most of its meshes, are written into the Sim's user IFF file. Unlike these other meshes, they can't be changed. Or rather, they can, but the game changes them right back when loading the Sim. This is a problem when a body type really needs custom hands, for instance, when the wrists are wider than the standard hands.

It is possible to add hand meshes to the head or body mesh as accessories. The texture used on such meshes will be either the body texture if the mesh name ends on "-BODY" and is included in the body CMX, or the head texture if the mesh name ends on "-HEAD-HEAD" and is included in the head CMX, or the name of the bitmap file in the hand mesh's own header otherwise. The hand mesh attached as accessory will not change from open to closed or pointing as the proper hand meshes do, and the proper hand meshes will still be visible, so the custom hand mesh should be large enough to contain and hide them. Also, custom hand textures that are loaded with an outfit because they have the same identifier will not be applied to these accessory hands.

Head texture files hardly have the space to include hand textures, but attaching the accessory hands to the head means they won't disappear when a Sim changes outfit or dress style. They can use the standard hand textures by having the texture name written in their header, although that does mean at least three copies of the same pair of hands is needed to write in the dark, medium and light textures. The hands that come with Jerome's SUM meshes use a different solution: they are included in the body CMX and mapped to two tiny areas on the body mesh, which means they can always be the right colour - custom colouring like "gloves" is included in the body texture itself - but they have to be included in every CMX for that body type to stop the hands disappearing, and as they're mapped to such a small area, the end result can look blurred. Moreover, as every skin for that body type needs these tiny hand textures, it has to be edited and can't be copied straight from the Fat skin. So my solution is to use warped hand meshes that have the standard hand skin names in their header, and attach them to the head; SUM needs custom head files anyway. If an outfit really needs gloves, I'll warp hands of a slightly larger size, put the glove skin name in their headers and include them in that outfit's body CMX.

Custom hand meshes, which would solve the problems above, are in fact possible: NPCs have them, and they are not flushed out on loading. This is because the IFF file of a NPC is not saved in the game. Pre-HD Sims are saved every time they change outfits; post-HD Sims are saved constantly. This is why post-HD Sims always revert to default hands (and nude body meshes) when the game is started, and why it is possible to give pre-HD Sims custom nudes and hands. These will stay in place as long as the Sim doesn't change clothes, which is hardly a workable solution.