Open Blender and you should see this upon opening the program. Open a general project, and find your avatar’s FBX file (your mesh)

After that you want to drag it and drop it into blender. upon dropping you’ll be greeted with a context menu, click the blue button that says ‘Import’ to import the file into blender.

If your avatar has different meshes for the main body like this (I’m using the Maruchi to show this) you’ll want to Shift + Left click the meshes in your viewport, right click to bring up a menu and click the option to ‘Join’ your meshes, shown in the image below.

Turning on proportional editing will save you a lot of time. While in Edit Mode, go to the top-middle of your viewport and click the icon that looks like a circle. Next, click the dropdown menu next to it and turn on “Connected only.” This feature makes it so you can move just the connected parts of the mesh you want, making it much easier to position and delete the objects you don’t need.

A good tip to make things easier is to select a viseme shape key that opens the mouth of the mesh, which prevents you from having to clip into it. To do this, go to the menu on the right side of your screen and click on the green triangle icon—it’s the second one from the bottom. From there, just select the “aa” viseme shape key.

After that’s done, you can select a small part of each individual mesh you want to remove and drag them to a new spot. This lets you Shift + Left-click and drag without accidentally selecting the rest of the mesh.
Once the unwanted parts are selected, press the Delete key on your keyboard and choose “Vertices.” You may need to repeat this process a few times to completely remove all the unwanted pieces.

So, i will assume you have your avatar set up already. find your new FBX file that you just exported, drag and drop it into the project tab on the bottom of your unity editor. and then drag that newly imported model into your viewport. (My exported mesh is pure white, the textured one is the actual avatar)

now, right click on the project window, hover over ‘Create’ then click on ‘Material’ and give it a name like ‘Outline’ to remember what it’s for.

Over in your inspector window you want to open your shader dropdown menu, and click

VRChat -> Mobile -> Toon Standard

Now, we want to make the color on the main texture black (or whatever color you want your outline to be)

Set it’s shading to Flat

And change culling from Back to Front.

and then you will have your material, Well done!

Now, click on your mesh renderer and change every material slot to your new outline material. and look at that! that is an outline that will work with standalone VRChat, BUT! you’re not done yet.

These are the import setting we want for the model category.

This is what we have. so make sure to match your outline’s import settings with your actual mesh’s and next. we want to make sure the rig’s match

This is the maruchi’s rig, humanoid and all. our outline by default is set to generic. this is bad!

First, in the Rig tab of your new model, click the dropdown menu that says “Generic” and change it to “Humanoid.”
This will give you the option to Apply and Configure the rig. Once you’ve applied the humanoid rig, click on the Configure button that appears and make sure all the bones in your new mesh are linked correctly, matching the bones in your main character’s rig.

next up you will want to drag the root of your outline and drop it onto the root of your avatar. and add a component. and search for ‘Armature Link’ and add the component.

Next you’ll want to add a blendshape link component.

The ‘Body’ in the text box will be the name of the renderer on your character

The BunnyTail will be the name of the renderer on your outline

As the maruchi has multiple renderers. we’ll need to add multiple of these components to link them all.

Since VRChat’s built-in viseme system is locked down for whatever reason, we’ll use a component called VRCFury’s Advanced Visemes to handle this.

On the root of your avatar in the Unity Hierarchy, click Add Component.

Search for “VRCFury” and select the “VRCFury | Advanced Visemes” component to add it.

In the new component, you will see a list of VRChat’s standard visemes (e.g., sil, PP, FF, TH, etc.).

For the first viseme, click the “Add action” button and select “Blendshape” from the dropdown menu.

The Advanced Viseme system is a bit more rigid than VRChat’s default. To avoid making your main character’s face look robotic or “jerky,” you must prevent this system from affecting anything but your outline mesh.

uncheck the box labeled “Apply to all renderers.” This ensures the blendshape action is not applied globally.

Locate the “Renderer” slot within the blendshape action you just created.

Drag and drop the renderer of your new outline mesh into this slot.

Click on the search button next to the “Blendshape” field.

A list of all the blendshapes on your outline mesh will appear. Find and select the blendshape that corresponds to the viseme you are currently setting up (e.g., for the “aa” viseme, select the “aa” blendshape).

Repeat steps 2 through 5 for every single viseme listed in the VRCFury component, making sure each one is linked to its matching blendshape on your outline mesh.