# How to Split a 3D Model into Parts with AI

Turn one solid mesh into separate, editable parts with AI: slice it into printable pieces with pins and holes, or separate it into complete layered parts for reuse. Step-by-step in Sloyd, plus how it compares with Blender, MeshLab and other AI tools.

_Martin Truong · 2026-10-30 · 3D Modeling_

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Most AI 3D models arrive as one solid piece. The robot's arm, its head and its torso are welded into a single [mesh](/glossary/mesh), so you cannot print the arm in another color, swap the head, or open the car door in your game without first cutting the model apart by hand.

This guide shows how to **split a 3D model into parts with AI** with [Sloyd Split to Parts](https://app.sloyd.ai/split-to-parts), and how that compares with Blender, MeshLab and other AI tools.

![Illustration: a whole toy robot on the left and the same robot split into parts (head, torso, hips, arms and legs) on the right](/blog-assets/how-to-split-a-3d-model-into-parts-with-ai/whole-vs-split-parts.avif)

## What Does It Mean to Split a 3D Model into Parts?

Splitting a 3D model into parts means turning one continuous mesh into several separate meshes, one per meaningful piece, such as a head, a wheel or a lid. Each part can then be moved, hidden, recolored, printed or exported on its own.

AI part splitting (also called 3D part segmentation) lets an AI model find the boundaries instead of you selecting faces by hand. That matters most for AI-generated and scanned models, which rarely come with separate objects.

## Why Split a 3D Model into Separate Parts?

You split a model when one solid piece blocks the next step: printing, animating, retexturing or reusing it.

- **Print in pieces or in several colors.** Parts that sit flat on the bed need fewer supports, and each part can get its own filament. New to print prep? Start with our [10 tips for print-ready AI models](/blog/10-tips-for-creating-print-ready-3d-models-with-ai).
- **Rig and animate mechanical parts.** A turret that rotates, a wheel that spins or a door that opens must be its own mesh before you can parent it to a bone (see [rigging](/glossary/rigging)).
- **Retexture one part.** Repaint only the helmet or the hull.
- **Kitbash.** Combine the wings of one spaceship with the cockpit of another.
- **Game interactivity.** Doors, lids, levers and wheels that move independently in Unity, Unreal, Godot or Roblox.

## How to Split a 3D Model into Parts with AI (Step by Step)

In Sloyd, you open Split to Parts, pick a model, choose a method and click **Generate Parts**. The result is a new model in your activity, with every part as its own mesh, ready to review, post-process and export.

### Step 1: Generate or upload the model

Start from a model you already have. Generate one with [text to 3D](/text-to-3d) or [image to 3D](/image-to-3d), or upload a file made in another tool. The Split to Parts page lists your recent models and has an upload area that accepts .blend, .dae, .fbx, .glb, .gltf, .obj, .ply, .stl, .usd, .usda and .usdc, up to 500 MB.

Hard-surface objects with clear joints, such as vehicles, robots, furniture and props, split best. A focused object generated with [LLM 3D Creation, Sloyd's LLM text-to-3D tool](/blog/llm-text-to-3d-vs-diffusion-text-to-3d), is a good candidate for exactly that reason.

If the model is very dense, reduce it first. The Partition method needs the model's GLB to be 16 MB or smaller, and our guide to [decimating AI models with Mesh Modifiers](/blog/mesh-modifiers-decimate-and-wack-ai-3d-models) shows how to cut the polygon count in the browser. Mesh Modifiers edits are not saved to the model, so export the decimated model as GLB, upload it on the Split to Parts page and split that uploaded copy.

### Step 2: Choose a split method

Split to Parts has a **Method** selector with two options. Pick by what you will do with the parts.

**Partition** slices across the model's surface into pieces that fit back together exactly. It is the method marked as ideal for 3D printing.

- Keeps the original polygons and textures.
- Closes every cut with a flat cap, so each part is a closed shell.
- **Number of parts** slider from 4 to 16 (default 6). The AI follows the model's natural parts, so the result can land up to 2 parts above or below your number.
- **Attachment points** switch adds a round pin on one part and a matching hole in the other at each join, so printed parts slot together. Joints without enough room for a pin are skipped.
- Takes about four minutes.

**Decomposition** separates the model into layers, each a complete part of its own. It is the method marked as ideal for reusable parts.

- Rebuilds surfaces hidden inside the model, such as a head under the hair or legs under a skirt, so parts can overlap and nest.
- The AI chooses the number of parts.
- Parts come back without textures and usually with more polygons than the source.
- Takes about two and a half minutes.

![Illustration of a character separated into complete layered parts: hair above a full head, a cloak lifted off a complete body, belt and boots separate](/blog-assets/how-to-split-a-3d-model-into-parts-with-ai/decomposition-layered-parts.avif)

### Step 3: Generate parts and review them

Click **Generate Parts**. The run costs 20 credits, shown on the button. Split results open slightly exploded, and the viewer's **Explode** slider pulls the parts further apart so you can inspect every cut.

Check that each boundary sits where it should (a wheel is one part, not half a wheel and half a fender), that there are no tiny slivers, and that the joints you care about got pins. If not, change the method or the part count and run it again on the original model.

### Step 4: Post-process the split model

On a split result, the viewer's **Post-processing** menu offers **Retexture** (new AI materials from a prompt, which is also how you texture a Decomposition result), **Edit Texture** and **Multicolor Print** for textured models.

Mesh Modifiers, Mounts & Keychains, Animate and Auto Rig are not offered on a split result, so run them on the original model. To turn a figure into a pendant or keyring, for example, use the [AI keychain and mount generator](/blog/ai-keychain-generator-3d-printed-keychains-and-mounts) on the unsplit model.

### Step 5: Export the parts

Export like any other model. The game-dev export offers GLB, FBX, OBJ, OBJ+MTL in a ZIP, USD, USDZ and BLEND, and in GLB every part arrives as its own mesh. The 3D print export offers 3MF, STL, OBJ, PLY and BLEND, and the Plugins tab adds Send to OrcaSlicer and Send to Bambu. See our [guide to Sloyd's export formats](/blog/a-guide-to-sloyd-s-export-formats-for-any-use-case).

Building a kit from several split models? Bulk export packs up to 16 models into one file. Each part is its own mesh, so turn the shared texture atlas off, or keep the total part count at 16 or fewer, because the atlas needs one cell per mesh. See our guide to [exporting multiple 3D models as one game asset pack](/blog/export-multiple-3d-models-as-one-game-asset-pack).

## Partition or Decomposition: Which Method Should You Use?

Use Partition when the parts must fit back together, as in a print, and use Decomposition when each part must stand on its own, as in a kitbash library or a character whose hair and clothing you want to swap.

![Illustration of a toy car split into body, chassis and wheel axles, with round pins on one part and matching holes on the other](/blog-assets/how-to-split-a-3d-model-into-parts-with-ai/printed-parts-with-pins.avif)

| Goal                                        | Method        | Why                                                                         |
| ------------------------------------------- | ------------- | --------------------------------------------------------------------------- |
| Print a large model in pieces               | Partition     | Flat caps, exact fit, optional pins and holes                               |
| Print in several colors, one part per color | Partition     | Keeps textures; print each part in its own filament or use Multicolor Print |
| Doors, wheels or lids that move in a game   | Partition     | Pieces keep their original shape and position                               |
| Swap hair, armor or clothing on a character | Decomposition | Rebuilds the surface hidden under each layer                                |
| Build a reusable kitbash library            | Decomposition | Each part is complete on its own                                            |

## What Makes a 3D Model Split Well?

A model splits well when its parts are visually distinct: clear joints, changes in shape, and creases between pieces. Smooth, fused shapes give the AI little to cut along.

- **A sensible part count.** Asking for 16 parts on a mug creates slivers.
- **Reasonable density.** Decimate very dense meshes first, then upload the exported GLB and split that copy.
- **Clean geometry.** Holes and non-manifold edges confuse any splitter. Our [checklist for preparing a 3D model for printing](/blog/essential-steps-for-preparing-a-3d-model-for-3d-printing) covers the basics.
- **One object per run.** Split a single prop, not a whole scene.

## AI Splitting vs Manual Methods: Blender, MeshLab and Other AI Tools

Manual tools split along boundaries already in the file, such as loose pieces or material slots. AI tools find boundaries that only exist in the shape, which is what a single welded mesh needs.

### Blender: Separate by Selection, by Material or by Loose Parts

Blender's **Separate** operator (Edit Mode, Mesh > Separate, shortcut P) splits a mesh into new objects in three ways, according to the Blender manual checked on 30 October 2026: **Selection** moves the faces you selected into a new object, **By Material** creates an object per material slot, and **By Loose Parts** creates an object for every disconnected piece.

**Pick it when:** the model already has loose pieces or one material per part, or you want full manual control. On a welded single-material AI mesh you are back to selecting faces by hand, with no caps or pins. Weighing other tools? See our [Blender alternatives roundup](/blog/10-best-alternatives-to-blender-for-3d-modeling-and-asset-creation).

### MeshLab: Split in Connected Components

MeshLab, the free open-source mesh processor, has a **Split in Connected Components** filter (Filters > Mesh Layer) that turns every disconnected piece into its own layer. Like By Loose Parts, it only finds pieces that are already separate.

**Pick it when:** you need a free way to separate a file that already consists of loose shells.

### Tripo Mesh Segmentation

Tripo's developer docs, checked on 30 October 2026, list a mesh segmentation endpoint with a geometry-based v1 (default) and a semantic v2 in Beta. It accepts GLB, GLTF, FBX, OBJ and STL up to 150 MB. The v2 Beta adds a granularity setting (simple, balanced or detailed) instead of a part count; the default v1 has none. Tripo's API pricing page lists segmentation as a per-task credit price; check it for the current rate.

**Pick it when:** you already generate with Tripo's API.

### 3D AI Studio Segmentation

3D AI Studio's Segmentation tool, per its docs checked on 30 October 2026, costs 15 credits per run in the web app (its API, which runs Tripo Segmentation, lists 80 credits per request), takes about 90 to 120 seconds, accepts GLB only (single mesh, single material) and returns a GLB with each part as a separate mesh. You cannot set the number of parts.

**Pick it when:** you already use 3D AI Studio.

### Hunyuan3D-Part (Self-Hosted)

Tencent's Hunyuan3D-Part pairs P3-SAM, which segments a mesh, with X-Part, which generates complete parts. The code and weights are published under the Tencent Hunyuan 3D-Part Community License, which does not apply in the EU, UK or South Korea. The GitHub repository notes that the public X-Part release is a light version. For transparency: Sloyd's Decomposition method runs on Tencent's hosted Hunyuan3D-Part service.

**Pick it when:** you are outside the EU, UK and South Korea, want to self-host, and can build your own pipeline.

### Split Methods Compared

| Tool                      | Finds parts in a single welded mesh | Part count control    | Pins and holes | Keeps textures | Price checked 30 Oct 2026           |
| ------------------------- | ----------------------------------- | --------------------- | -------------- | -------------- | ----------------------------------- |
| Sloyd Split to Parts      | Yes, Partition or Decomposition     | 4 to 16 (Partition)   | Yes            | Partition: yes | 20 credits on Sloyd Plus or Pro     |
| Blender Separate          | Only by hand selection              | Manual                | No             | Yes            | Free                                |
| MeshLab                   | No, loose pieces only               | No                    | No             | Yes            | Free                                |
| Tripo Mesh Segmentation   | Yes                                 | Granularity (v2 Beta) | Not stated     | Not stated     | Per-task credits (API pricing page) |
| 3D AI Studio Segmentation | Yes                                 | No                    | Not stated     | Not stated     | 15 credits per run (web app)        |
| Hunyuan3D-Part            | Yes                                 | No (automatic)        | Not stated     | Not stated     | Self-hosted                         |

"Not stated" means the vendor's page did not say, not that the feature is missing.

## Split Models Automatically with the API, MCP or Agent

The same split is available outside the app, so a pipeline or an AI agent can run it.

- **API:** `POST /jobs/split-to-parts` takes the `jobId` of a model you own, plus optional `method` (`partition` or `decomposition`), `numberOfParts` (integer, 4 to 16, default 6) and `attachmentPoints` (boolean, default false). Upload external models first with `POST /jobs/upload-3d` (GLB, OBJ, FBX, STL, BLEND, PLY, USDC or USDA, up to 500 MB). A split costs 40 API credits, which are prepaid at 75 credits per USD, and failed splits are refunded. See the [Sloyd API page](/api), [API pricing](/api/pricing) and our comparison of the [best 3D model generation APIs](/blog/best-3d-model-generation-apis).
- **MCP:** the Sloyd MCP server exposes the same endpoint as the `split_model_into_parts` tool, so Claude Code, Codex, Cursor, VS Code or Claude Desktop can call it. Set it up from the [in-app MCP page](https://app.sloyd.ai/mcp), and read our guide to the [best MCP servers for 3D model generation](/blog/best-mcp-servers-for-3d-model-generation).
- **Agent:** subscribers can ask the Sloyd [Agent](https://app.sloyd.ai/agent) (Beta) to split a model with Partition, with optional part count and pins, as part of a longer task. Our roundup of the [best AI agents for creating game assets](/blog/best-ai-agents-for-creating-game-assets) shows where it fits.

## Common Mistakes When Splitting a 3D Model

Most failed splits come from picking the wrong method, asking for too many parts, or uploading a GLB over Partition's 16 MB limit.

- **Using Decomposition for a print.** Decomposition parts overlap and nest and have no textures. For pieces that fit back together, use Partition.
- **Asking for too many parts.** Match the part count to the object, or you get slivers.
- **Forgetting Attachment points.** Without pins and holes, printed parts need glue and careful alignment.
- **Expecting to rig the split result in Sloyd.** Auto Rig and Animate run on the whole model. For characters, rig the original with [AI animations](/animations); for mechanical parts, parent the split meshes in your engine or DCC. Our guide on [rigging AI models for animation](/blog/how-to-rig-ai-models-for-animation-in-minutes) covers both.
- **Uploading an oversized mesh.** Partition rejects GLBs over 16 MB. Decimate, export the GLB and upload it back before you split.

## FAQ

### How do I split a 3D model into parts?

Open Split to Parts in Sloyd, pick or upload a model, choose Partition or Decomposition, and click Generate Parts. Partition takes about four minutes, Decomposition about two and a half. The result is a new model where every part is its own mesh, ready to retexture, print or export.

### Can AI separate a 3D model into parts automatically?

Yes. AI part segmentation finds the natural parts of a single welded mesh, such as a head, wheels or a lid, and separates them without manual face selection. Sloyd, Tripo, 3D AI Studio and Tencent's self-hosted Hunyuan3D-Part all do this, with different controls, outputs and licenses.

### How do I split an STL for 3D printing?

Upload the STL to Sloyd Split to Parts, choose Partition, set the number of parts and turn on Attachment points for pins and holes. Each cut is closed with a flat cap, and you export to 3MF or STL or send the result straight to OrcaSlicer or Bambu.

### How do I separate a mesh into parts in Blender?

In Edit Mode, open Mesh > Separate or press P, then choose Selection, By Material or By Loose Parts. By Loose Parts and By Material only work when the pieces or materials are already separate. On a single welded mesh you select faces by hand, and Blender does not cap the openings.

### How many parts can Sloyd split a model into?

With Partition, you choose from 4 to 16 parts, with 6 as the default. The AI follows the model's natural parts, so the result can be up to 2 parts above or below your choice. With Decomposition, the AI decides the number of parts from the shape.

### Does splitting keep the textures?

Partition keeps the original polygons and textures and gives each cap the part's material. Decomposition returns untextured parts, usually with more polygons than the source, because it rebuilds hidden surfaces. Retexture puts a texture back on a Decomposition result.

### Do I need a paid plan to split a model?

The Split to Parts page is open to every signed-in user, but generating parts needs Sloyd Plus ($15/month) or Sloyd Pro ($50/month). Each split costs 20 credits. Plus includes 50 credits a month and Pro 350, and you can buy top-up credits that carry over. Through the API, a split costs 40 prepaid credits.

## Split Your First Model into Parts

Open [Split to Parts in the app](https://app.sloyd.ai/split-to-parts), or generate a model to split with [text to 3D](/text-to-3d) or [image to 3D](/image-to-3d). Printing the parts? See [3D for 3D printing](/use-case/3d-printing) and add a keyring or stand with the [keychain and mount generator](/blog/ai-keychain-generator-3d-printed-keychains-and-mounts). Shipping a game? See [3D for game development](/use-case/game-development), slim the model down with [Mesh Modifiers](/blog/mesh-modifiers-decimate-and-wack-ai-3d-models), then export and upload the GLB before you split, and pack the results with bulk export, keeping a [shared texture atlas](/glossary/texture-atlas) to 16 parts or fewer. Automating it? Start with the [Sloyd API](/api) or the [MCP server](/blog/best-mcp-servers-for-3d-model-generation), and compare plans on the [pricing page](/pricing).

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Source: https://www.sloyd.ai/blog/how-to-split-a-3d-model-into-parts-with-ai