#posemaking tutorial

Basics:

For the purposes of this, I'm going to assume you know how to use SimRipper and blender at least a little bit. If you've never made a custom rig, this tutorial by @rebouks is a great place to start!

To follow this tutorial, you're going to need the following:

SimRipper

Blender (version of your choice, but remember that only certain versions technically work with s4s. Those include 2.78, 2.79, and anything above 3.3. I personally use 2.79, but that's because I don't like change.)

A sim of your choice, with multiple outfits, placed on any lot in any save.

Let's get started!

First Steps:

First off, you're going to need to rip your sim. Follow the tutorial I linked above to get your sim ripped, and into blender. Once you have your custom rig set up, we're ready to continue.

Optional Step 1: IK Chains

So, before you continue with this tutorial, there's something really easy you can do that will make pose-making much easier! Two things, actually. One of them is setting IK chains, and the other is locking the finger joints.

Setting IK chains means that when you move your sim's foot or hand, their whole arm moves with it, in a natural and logical way. This makes posing arms and legs SO much faster and easier.

To do it, select your sim's hand or foot joint, then go to the Bone Constraints tab in the side bar. Hit "add Bone Constraint" and select "Inverse Kinematics".

Then change the "chain length" setting to 3.

Now go back to the rig, hit "g" and see if your sim's arm moves, not just the hand. If it does, congrats, you did it! Now go through and do it for the other hand and feet.

Optional Step 2: Locking the Fingers

Sometimes when posing, you bend a finger from one direction, only to look at it from another angle and find that it looks broken. Luckily, there's an easy way to make sure that doesn't happen. (Credit to @ratboysims for the original tutorial on how to do this, but it seems to have been deleted.)

Select any of your sims' finger joints. I usually do the 1 and 2 joints, but not the 0 joint, but that's just personal preference. Hit the small plus sign at the top right of your screen to bring up the transform panel.

Under where it says "rotation", toggle the lock icons so that all of them except for the Z are locked.

Now when you rotate your sims' fingers they should only bend up or down, not side to side. If you need to bend them side to side for a specific reason, just unlock the locks, adjust the finger, and lock them again.

TIP: I advise having a blank, uncustomized rig that has the IK chains and locked fingers already done. That way, every time you make a custom rig, you don't have to redo this.

Now onto the part I was actually asked about...

Adjusting the Height:

If your sims are canonically different heights, you're going to want to keep that consistent when you pose them. Adjusting your sims' height in blender is SUPER easy!

Just right-click on any of the joints I've circled here:

Once you have the joint selected, 3 different colored arrows will show up. (If you're looking at them head-on, you'll only see two. That's normal!) Select the blue one, and drag it up or down.

It's important to use the arrows rather than simply the "g" key. This will ensure that your sim isn't crooked.

TIP: Use a combination of all the points I showed above to get a more "realistic"-looking sim. If you only manipulate one or two, you'll end up with some very odd proportions.

Here's an example of what I was able to achieve using height manipulations. The sim in the middle, Nina, is the default height.

Once you have your sim at their desired height, save your file!!! (In case something goes wrong later, or you don't want to add more outfits, you won't have to redo it.)

Adding Additional Outfits

One of the biggest benefits of a custom rig is being able to ensure there is zero clipping by using the exact outfit and hair that your sim is going to wear. But your sim isn't going to be wearing the same outfit in every picture. And what if they're wearing black? Or a dress? Something that makes it hard to see the joints in blender? That's where having multiple outfits on the same rig is helpful.

Export your 2nd (or 3rd, etc.) outfit from SimRipper. This should follow the same process you did the first time. You can choose which outfit to export by clicking on the dropdown menu labeled "outfit".

Save the file as a DAE as normal. If you're saving it in the same folder as the first one (and you haven't deleted the first one), you'll have to name it something different, or put it in it's own subfolder. I tend to name mine something like "[sim name] - Formal" to make it obvious which is which.

Open your custom rig in blender. Go to "file > import > collada (DAE)" and select your new outfit.

This is exactly like importing it the first time, so you can follow the exact same steps. The only different is that now you will have multiple of them.

If you didn't rename the DAE itself, your sidebar should look something like this. (You'll only have two, and also may or may not have the glass versions, depending on if your sim has transparency on any of their outfit.)

Rename those little sub-files into something more descriptive, so you know what you're looking for.

Looking at your sim, it might look a little wild, because all the outfits are overlapping. Just toggle the eye icons so that only the outfit you want to be working with is showing.

Repeat as many times as you want to have as many outfits as you need. (Feel free to delete any outfits you don't need after using them, etc.)

TIP: Have a "naked" version of your sim (aka, them in a swimsuit or underwear) for easy selection of joints and easier viewing of pose details. This is especially helpful if your sim is wearing something that obscures part of the rig (ex: a floor-length dress) or a dark color that hides the joints.

You did it! Now save your file, take a break, get a snack and a drink, and get to making poses! (Make sure you save a version with your sim unposed and at the correct height so you can use it as a base for every single pose. That is the whole point of this, after all!)