How to rig an AI-generated 3D model for free

Short answer: an AI 3D generator gives you a statue. To make it walk, it needs a skeleton and skin weights, which is called rigging. For a humanoid character, the easiest free route is Mixamo: upload an FBX, place a few markers, and download a rigged character you can use in a commercial game. If Mixamo fails, try AccuRIG (a free desktop app) or Blender's built in Rigify add-on, which also handles animals. Tripo can rig inside its free plan, but free Tripo models are non-commercial. Clean up and scale the model first, and most rigging problems go away. Every plan, limit and license detail below comes from each company's own pricing pages, help centers, docs and manuals, checked October 28, 2026. We only cover free plans.

The 30 second version

• Make it rig friendly: one connected humanoid mesh, T-pose or A-pose, arms away from the body, about 1.8 m tall, feet at the origin.
• Humanoid? Mixamo first. Free, royalty free for games, humanoids only.
• Mixamo fails? AccuRIG, a free desktop auto-rigger with adjustable joint guides and hand rigs.
• Animal, creature or full control? Blender Rigify plus automatic weights. Free and open source.
• Made it in Tripo and only practicing? Rig it right there on the free plan, but do not ship it.
• Export: GLB for Godot, FBX for Unity and Unreal.

Free rigging options compared

Free plans only, from each tool's official site, checked October 28, 2026.

Tripo's 15 free exports and its rigged export formats come from its pricing page and auto-rigging page. We could not confirm whether exporting a rigged model counts against the 15 exports, so assume it does.

Step 1: get a model that wants to be rigged

Most failed rigs are caused by the model, not the rigger. If you are generating the character, ask for it in a T-pose or A-pose. Meshy's rigging docs say the best result comes from a T-pose or A-pose with a clear gap between the limbs and the body. If you are picking a generator, see Best free AI 3D model generators for game assets, Meshy vs Tripo and Tripo vs Rodin. StudioTwin also makes image to 3D meshes on its free plan. Its site covers text-to-motion for characters and MetaHumans in Unreal, but we did not find an auto-rigger for your own mesh listed, so rig a StudioTwin mesh with one of the routes below.

Adobe's Mixamo FAQ has the best checklist we found, and it applies to every auto-rigger:

• A humanoid with a clear head, body, arms and legs.
• No large extras like wings, tails, big hair, long coats or props in the hands.
• A default or neutral pose, not a very asymmetric or action pose.
• Nothing else in the file: no cameras, helper objects or other scene objects.
• No gaps between parts. A floating head that is not joined to the body breaks it.
• Centered at the world origin (0, 0, 0).
• A clean, error free mesh.

Step 2: clean up and scale it in Blender (free)

AI models are often far too dense, split into parts, off center and the wrong size. Fix that in Blender before you rig. In Blender's words, the Decimate modifier in Collapse mode merges vertices while keeping the shape, and its Ratio is the share of faces to keep. Rigify's manual assumes 1 unit is 1 meter, so a human is about 2 units tall, and suggests scaling the character and then applying the scale before you rig.

This script does all of it at once. It imports a GLB, FBX or OBJ, deletes everything that is not a mesh, joins the parts, welds duplicate vertices, decimates to a triangle budget, scales the character to a height you choose, puts its feet on the ground at the origin, and exports an FBX with textures embedded, which is what Mixamo wants. We tested it on Blender 5.2.3 LTS with a dense, off center, five part test character that included a camera: it came out as one mesh, 1.80 m tall, centered, at the triangle budget.

# prep_for_rigging.py: clean up an AI-generated character before auto-rigging.
# Run: blender --background --python prep_for_rigging.py -- in.glb out.fbx 1.8 30000
import bpy, sys, math
from mathutils import Vector

argv = sys.argv[sys.argv.index("--") + 1:]
src, dst = argv[0], argv[1]
height = float(argv[2]) if len(argv) > 2 else 1.8       # target height in meters
max_tris = int(argv[3]) if len(argv) > 3 else 30000     # triangle budget

bpy.ops.wm.read_factory_settings(use_empty=True)
if src.lower().endswith((".glb", ".gltf")):
    bpy.ops.import_scene.gltf(filepath=src)
elif src.lower().endswith(".fbx"):
    bpy.ops.import_scene.fbx(filepath=src)
else:
    bpy.ops.wm.obj_import(filepath=src)

# Keep meshes only: no cameras, lights, empties or old armatures.
meshes = [o for o in bpy.context.scene.objects if o.type == "MESH"]
for o in list(bpy.context.scene.objects):
    if o.type != "MESH":
        bpy.data.objects.remove(o, do_unlink=True)

# Join everything into one mesh and apply transforms.
bpy.ops.object.select_all(action="DESELECT")
for o in meshes:
    o.select_set(True)
bpy.context.view_layer.objects.active = meshes[0]
if len(meshes) > 1:
    bpy.ops.object.join()
obj = bpy.context.view_layer.objects.active
obj.name = "Character"
bpy.ops.object.transform_apply(location=True, rotation=True, scale=True)

# Weld duplicate vertices so the body is one connected surface.
bpy.ops.object.mode_set(mode="EDIT")
bpy.ops.mesh.select_all(action="SELECT")
bpy.ops.mesh.remove_doubles(threshold=0.0001)
bpy.ops.object.mode_set(mode="OBJECT")

# Decimate down to the triangle budget.
tris = sum(len(p.vertices) - 2 for p in obj.data.polygons)
if tris > max_tris:
    mod = obj.modifiers.new("Decimate", "DECIMATE")
    mod.ratio = max_tris / tris
    bpy.ops.object.modifier_apply(modifier=mod.name)

# Scale to the target height (1 Blender unit = 1 meter), feet on the ground, centered at the origin.
zs = [v.co.z for v in obj.data.vertices]
obj.scale *= height / (max(zs) - min(zs))
bpy.ops.object.transform_apply(scale=True)
xs = [v.co.x for v in obj.data.vertices]; ys = [v.co.y for v in obj.data.vertices]; zs = [v.co.z for v in obj.data.vertices]
obj.location -= Vector(((min(xs) + max(xs)) / 2, (min(ys) + max(ys)) / 2, min(zs)))
bpy.ops.object.transform_apply(location=True)

tris = sum(len(p.vertices) - 2 for p in obj.data.polygons)
print(f"prep: {tris} triangles, height {max(v.co.z for v in obj.data.vertices):.2f} m")

# FBX with textures embedded, which Mixamo needs to show your textures.
bpy.ops.export_scene.fbx(filepath=dst, use_selection=False, path_mode="COPY", embed_textures=True)
print("prep: wrote", dst)

Run it from a terminal, with your file names, height in meters and triangle budget:

blender --background --python prep_for_rigging.py -- hero.glb hero_for_rigging.fbx 1.8 30000

The triangle budget is your call. Lower is faster in the game but loses detail. Look at the result before you rig: open the FBX in Blender and turn on the Statistics overlay. If welding did not join a floating part (like a head that was a separate shell), move it until it touches the body or join it by hand. To have an AI coding agent write and run scripts like this for a whole folder, see How to use Claude Code with Blender for game assets.

Step 3, route A: Mixamo (best free option for humanoids)

From Adobe's Mixamo rigging help and FAQ, checked October 28, 2026:

1. Log in to mixamo.com with an Adobe ID. It is free and needs no Creative Cloud subscription. It is not available for Enterprise or Federated IDs, or for users with a China country code.
2. Click Upload Character and pick your FBX, OBJ or ZIP. For an FBX, turn on embed media so your textures come along (the script above does this). An OBJ has no textures, so zip it with its .mtl and texture files.
3. Place the markers on the chin, wrists, elbows, knees and groin, and confirm. Rigging usually takes a few minutes.
4. Download the rigged character, or click Find Animations to add moves first.

Two things to know. Mixamo only stores your last character, so save every rigged character on your computer. And a model that was already rigged must be an FBX to upload. Mixamo then maps its skeleton so you can apply animations. What to do next with the animations is in How to animate a 3D character for free, and Mixamo vs Cascadeur compares the two for animation.

Step 3, route B: AccuRIG (free desktop auto-rigger)

Use AccuRIG when Mixamo will not rig your character or you want more control over the joints. Reallusion describes it as free software that rigs a humanoid in five steps, works with low to high density models in an A or T pose, and places joint guides for you that you can adjust, with a hand rig and a choice of finger count. The AccuRIG 2 install guide says you log in with a Reallusion account. When you are done, the export page offers FBX for Unreal, Unity, Blender, Maya, Cinema 4D, MotionBuilder and 3ds Max, or USD for Omniverse.

Limits of the free version, from Reallusion's own comparison table: it can import a character made of several meshes but cannot rig them separately, and it has no skin weight editing or mesh reduction. Those are in the paid Character Creator. AccuRIG also shows motions from the ActorCore store, and the manual has an Add to Cart step for motions before export, so do not assume every motion is free.

License: we could not find a license page for the free AccuRIG app. On Reallusion's forum, its staff have said that if a character is 100% your own creation with no Reallusion content, you can sell it after rigging in AccuRIG. Check Reallusion's terms when you install it before you rely on that.

Step 3, route C: Blender Rigify and automatic weights (free, any shape)

Blender can rig anything, including animals and creatures that Mixamo and AccuRIG cannot. The Rigify add-on is bundled with Blender (enable it in Preferences, Add-ons). From the Rigify basic usage page in the Blender 5.2 LTS manual:

1. Add a meta-rig: in Object Mode, Add, Armature (Shift A). Choose Basic Human (no face or fingers, simplest), Human, Basic Quadruped, Cat, Wolf, Horse or Shark.
2. Fit the bones to your character. Keep the legs and spine as straight as you can in the front view, and give the knees and elbows a slight bend so Rigify knows which way they point.
3. Generate: back in Object Mode, open the Armature tab and click Generate Rig.
4. Bind the mesh: select the mesh, then the generated rig, press Ctrl P and pick Armature Deform, With Automatic Weights. Rigify's manual says automatic weights usually do a really good job if the bones are placed well and the mesh has enough topology.
5. Test it: pose the rig in Pose Mode. If parts bend wrong, the Blender manual says you will need to fix the vertex weights by hand with weight painting.

We ran this whole route headless on Blender 5.2.3 LTS on the cleaned test character (Basic Human meta-rig, Generate Rig, automatic weights, GLB export) to make sure the steps work. A generated Rigify rig has many control bones. Only the deform bones (in the DEF bone collection) move the mesh, so export only those, as shown below.

Rigify rigs are built for animating in Blender. For a game, a simple skeleton is often easier: you can also add a single armature and bones by hand, then bind with automatic weights the same way.

Step 3, route D: rig inside the generator

Tripo (free, but non-commercial)

Tripo's pricing page (checked October 28, 2026) shows Rigging and Animation on every plan, including Free, and its credit table lists Auto Rig at 20 credits. Free gives 200 credits a month, 15 exports (H2.5 model only) and storage for 10 models. Tripo's auto-rigging page says it rigs humanoids and creatures, with skin weights, and exports rigged models as FBX, GLB or OBJ. The catch: free models are public and non-commercial, and Tripo's help center says Tripo keeps all rights to free users' inputs and outputs. Great for learning, not for a game you sell. Pro is $20 a month with commercial use.

Meshy (rigging on Free, downloads limited)

Meshy's rigging docs (checked October 28, 2026) show the Rig flow on the Free plan: pick Humanoid, Quadruped Dog, or Smart Rig (beta) for other shapes and drag markers to the chin, shoulders, elbows, wrists, groin, knees and ankles. You can rig a model you uploaded (FBX, OBJ, STL, glTF or GLB, up to 100 MB). Models over 300,000 faces must be remeshed first. Meshy's animation docs say downloads come as FBX, GLB or USDZ, with a Mixamo skeleton template by default for humanoids, and a few motions are on every plan.

The catch is downloading. Meshy's help center says Free can only download up to 10 untextured Meshy 6 Lite models a month, and textured models, models from Meshy 6, Meshy 7 or T2.5, textures on an uploaded model, and 3D Agent models cannot be downloaded on Free. It does not say whether a rigged character counts, so we could not confirm a free way to get a rigged Meshy character into your game. Free Meshy models are CC BY 4.0, so credit Meshy if you use one. Pro is $20 a month, often $10 for the first month.

Cascadeur (learning only)

Cascadeur's Free plan includes rigging tools, but it exports to .casc only, not FBX or DAE, and allows no commercial use. Fine for practicing, not a way to get a rigged character into your engine.

Step 4: export the rigged character to your engine

• Godot: GLB. Godot's 3D formats page lists glTF 2.0 as recommended, and can also import FBX through the built in ufbx importer. From Blender, use File, Export, glTF 2.0 and choose glTF Binary. For a Rigify rig, turn on Export Deformation Bones Only in the Armature options (see Blender's glTF manual) so the control bones stay out of your game.
• Unity: FBX. Unity's model formats page says Unity uses FBX as its internal import format. Select the model, open the Rig tab, and set Animation Type to Humanoid. Unity's Avatar docs say a humanoid needs at least 15 bones, and a proper T-pose gives better results.
• Unreal Engine: FBX. Unreal's FBX content pipeline imports skeletal meshes, animation and morph targets, and uses FBX 2020.2. From Blender, the FBX exporter has Only Deform Bones and Add Leaf Bones options in its Armature settings.

Retargeting (playing animations made for one skeleton on another) is covered engine by engine in How to animate a 3D character for free. Building in three.js instead? How to make a cozy walking game in three.js with AI loads a rigged GLB with tested code.

When the rig looks wrong

• Mixamo or AccuRIG will not rig it: check the Step 1 checklist. Remove props and wings, join floating parts, and center the model.
• Bones in the wrong place: the pose is too far from a T-pose or A-pose. Regenerate the character in that pose, or move the markers or joint guides and rig again.
• The mesh stretches or clips when it moves: the skin weights are off. In Blender, fix them with weight painting. With an auto-rigger, try a cleaner, lighter mesh from Step 2 and rig again.
• Arms stuck to the body: there is no gap between the arms and the torso. Regenerate with the arms out.
• Character is tiny or huge in the engine: scale to real size in meters and apply the scale before rigging, as the script does.

Before you ship: license checklist

1. The mesh: rigging does not change its license. Tripo Free models are non-commercial. Meshy Free models are CC BY 4.0 (credit Meshy). Check the rest in Can I sell a game made with AI art?
2. Mixamo rig and animations: royalty free for video games, per Adobe.
3. Blender: free software. Its license page says you are free to sell your work.
4. AccuRIG: no license page found for the free app. Check Reallusion's terms when you install it.
5. Your reference image: do not turn fan art or someone else's character into a model for a game you sell.

Sources, checked October 28, 2026: Adobe Mixamo FAQ, Mixamo rigging help, Tripo pricing, Tripo auto-rigging, Tripo commercial use help, Meshy rigging docs, Meshy animation docs, Meshy free plan help, AccuRIG, AccuRIG install guide, AccuRIG export, Cascadeur plans, StudioTwin, Rigify basic usage, Blender Armature Deform, Blender Decimate, Blender glTF, Godot 3D formats, Unity model formats, Unity Avatar, Unreal FBX pipeline.

Related

Next step after rigging: How to animate a 3D character for free. Need a model first? Read Best free AI 3D model generators for game assets, Meshy vs Tripo for 3D game assets or Tripo vs Rodin for 3D game assets. Browse every animation tool and 3D model and texture tool, or grab a free CC0 character from the free asset libraries.

FAQ

What is the easiest free way to rig an AI-generated character?

For a humanoid, Mixamo. Upload an FBX, OBJ or ZIP, place markers on the chin, wrists, elbows, knees and groin, and Adobe's auto-rigger builds the skeleton in a few minutes. It is free with an Adobe ID, and Adobe's FAQ says its characters and animations are royalty free in commercial projects, including video games. Checked October 28, 2026.

Can Mixamo rig an animal, a dragon or a robot with extra arms?

No. Adobe says the auto-rigger is for bipedal humanoids only, and that wings, tails, extra limbs, or large hair and clothing may stop it from working. For creatures, try Tripo, whose auto-rigging page says it rigs humanoids and creatures, or rig it yourself in Blender with a Rigify meta-rig such as Basic Quadruped, Cat, Wolf, Horse or Shark.

Is rigging included on Tripo's free plan?

Yes. Tripo's pricing page shows Rigging and Animation on every plan, including Free, and lists Auto Rig at 20 credits. Free gives 200 credits a month and 15 exports (H2.5 model only). The catch: free models are public and non-commercial, and Tripo's help center says Tripo keeps all rights to free users' inputs and outputs. Checked October 28, 2026.

Can I rig a character on Meshy's free plan?

Meshy's docs show the Rig button on the Free plan, and you can rig a model you uploaded. Downloading is the problem. Meshy's help center says Free can only download up to 10 untextured Meshy 6 Lite models a month, and textured models need a paid plan. It does not say whether a rigged model you uploaded counts, so we could not confirm a free way to download a rigged Meshy character. Pro is $20 a month. Checked October 28, 2026.

Should I use a T-pose or an A-pose?

Either works for the tools we checked. Meshy and AccuRIG both say a T-pose or A-pose gives the best result, and Mixamo asks for a default or neutral pose. Unity's humanoid import says a proper T-pose gives better results when it maps bones. If you generate the character, ask for a T-pose or A-pose with a clear gap between the arms and the body.

Which file should I export for Godot, Unity or Unreal?

GLB for Godot, since Godot's docs recommend glTF 2.0. FBX for Unity, since Unity's docs say it uses FBX as its internal import format. FBX for Unreal, whose FBX pipeline handles skeletal meshes and animation and uses FBX 2020.2.

Can I sell a game with a character I rigged for free?

The rig does not change the model's license. Mixamo's output is royalty free for games, per Adobe, and Blender is free software that lets you sell your work. But a model from Tripo's free plan is still non-commercial, and a model from Meshy's free plan is still CC BY 4.0, so you must credit Meshy. Check where the mesh came from first.