Skalin DNA Studio — MetaHuman Customizer for Blender

Version 0.9.0 Beta · Windows x64 · Blender 5.2+ · Unreal Engine 5.6–5.8

This documentation is a living document. It is updated and improved alongside the add-on itself — sections may be expanded, corrected, or reorganized as new versions ship and as user feedback comes in. If something here doesn't match what you see in the add-on, check for a newer version of both.

1. Overview

Skalin DNA Studio turns Blender into a full customization studio for Unreal Engine MetaHumans. It imports a MetaHuman's DNA files — the same files the engine itself uses to define the character — rebuilds the complete character inside Blender (every mesh, every LOD, both skeletons, materials with Unreal's exact slot names), and lets you change nearly everything about it. When you're done, it writes your changes back into a valid DNA file plus matching FBX exports that drop straight into the engine.

The one idea to internalize: the DNA file is the ground truth. Skalin DNA Studio never invents a character format of its own — every import reads Epic's own RigLogic data, every export is a format-faithful transformation of the file you started from. That is why exports rebind materials, morphs and rig behavior in Unreal without manual repair.

2. Requirements & Compatibility

2.1 Blender

2.2 Unreal Engine

2.3 System

• Windows x64 only. Linux and macOS are not currently supported. The bundled native RigLogic bindings target Windows x64 and Python 3.13.
• Nothing else — for anything. Import, export, synchronizing, sculpting, expressions, RBF editing: the entire workflow runs on Blender plus the bindings that ship inside the add-on. Python, SWIG, CMake and Visual Studio are never used at runtime — they exist solely to compile the bindings, which has already been done for you. You do not need them installed before, during or after installing the add-on.
• The one exception is rare and covered in §11: if the bundled bindings cannot load on your specific setup, they can be rebuilt locally (§11) — only then does a build toolchain enter the picture.

3. Installation

The add-on ships with prebuilt RigLogic bindings — installation is the zip and a restart, nothing more. (If the bindings ever fail to load on your machine — a rare case the add-on reports explicitly — see §11 for the rebuild procedure. It is deliberately not part of installation.)

1. Install the extension. In Blender: Edit → Preferences → Get Extensions → top-right dropdown → Install from Disk… → select SkalinDNAStudio_0.9.0_Beta_Full.zip (the zip file itself, not extracted contents).
2. Leave the Bindings Folder preference empty. Under Preferences → Add-ons → Skalin DNA Studio, the Bindings Folder field stays blank — the bundled bindings are found automatically. Press the recheck button; it should report the bindings as loaded.
3. Restart Blender. Required once after installation, and after every future update — compiled bindings cannot hot-reload inside a running Blender.
4. Verify. Open the 3D viewport sidebar (N) — a Skalin DNA Studio tab should be present. Press Validate Setup in the Import panel for a full health check.

That's the whole installation. Continue to §4 for your first character.

3.1 Updating & moving machines

• Updating: install the new zip over the old one (same Install from Disk flow), restart Blender. Preferences are preserved. If release notes say the import structure changed, re-import your DNA into a fresh scene.
• Moving to another PC: install the extension there (prebuilt bindings travel inside it — nothing to rebuild). Copy your character content folder and any working .blend files. If the DNA files live at a different path on the new machine, update the head/body DNA paths in the Import panel before enabling the Control Rig — saved scenes reconnect to their DNA through those paths.

4. Character Content

4.1 Getting the folder from Unreal

In Unreal Engine (5.6+), use the MetaHuman DCC export on your character. The result is a self-contained folder — call it anything; these docs use MHBase\:

MHBase\
├── head.dna            ← facial rig, meshes, blend shapes, neck RBF
├── body.dna            ← body rig, meshes, 72 RBF corrective solvers
├── Maps\               ← skin textures: Basecolor, Normal, animated CM/WM maps
└── SourceAssets\masks\ ← per-region wrinkle-map masks (drives the Animated preview)

Why the layout matters: Skalin DNA Studio auto-discovers Maps\ and SourceAssets\masks\ next to the DNA files. Keep the folder intact and materials come up textured with zero configuration. Every texture can also be overridden manually in the Materials panel.

4.2 First import — the smoke test

1. Skalin DNA Studio tab → Import DNA panel → set the head and body DNA paths (or simply drag the .dna files into the viewport — they land in the right slots automatically).
2. Press Import DNA. Every mesh at every LOD, both armatures, bone collections and slot-correct materials are built. The first run bakes wrinkle-map masks and takes a few extra seconds.
3. Edit Meshes panel → Create Edit Meshes.
4. Control Rig panel → Build Face Board, then Enable Control Rig. Drag any control on the board — if the face moves, the entire pipeline is verified.

5. Core Concepts

Five ideas explain every behavior in the add-on.

5.1 Edit meshes — where all work happens

Import gives you the character's originals: every part at every LOD, exactly as the DNA defines them. You never sculpt those. Create Edit Meshes builds one edit mesh per part at LOD0 quality — skin (head and body welded into one seamless mesh), eyes (both eyes in one object), teeth, eyelashes, eyeshell, eyeEdge, cartilage, saliva.

All editing happens on edit meshes. The originals and their LODs only change when you press Synchronize, which flows edit-mesh changes outward. This one-way flow is what makes the system safe.

The topology contract (critical): never add, delete, merge or reorder vertices on an edit mesh. Vertex index order is the link back to the DNA. Sculpting, moving vertices, proportional editing — all fine. Topology changes — never.

5.2 Secondary meshes — parts that follow

Eyelashes, eyeshell, eyeEdge, cartilage and saliva are rarely sculpted directly. After you sculpt the skin (or teeth), the Secondary Meshes panel conforms their edit meshes to follow the donor's deformation. By default everything follows the skin; saliva follows the teeth. Custom meshes you've added to the character can be conformed the same way.

5.3 Synchronize — the outward flow

One button applies your edit-mesh work to the whole character: LOD conform for every part, head↔body neck-seam snapping on the LOD pairs Unreal actually renders together, blend shape transfer, expression and armature updates, and an automatic seam-welded custom-normals pass. It is the last step before every export.

5.4 Names — Blender side vs Unreal side

5.5 Where your work lives — the three layers

The two save rules: save the .blend after applying expression or RBF edits. Export DNA to make changes permanent — and export to a new file, never over your source DNA.

6. Interface Reference

Every panel in the Skalin DNA Studio sidebar tab, in order.

6.1 View

6.2 Scene & Import DNA

Character name; head/body DNA paths; Import DNA. Drag .dna files into the viewport to set the paths. DNA File Info inspects the configured files (name, mesh/joint/blend shape/RBF counts) before importing. Validate Setup checks the entire installation and scene — bindings, paths, sessions, edit meshes, snapshots, topology integrity, board — and states exactly what's wrong, in a popup and the console. It's the first button to press when anything misbehaves, and the output to include in a support request.

6.3 Materials

Every material is named exactly like its Unreal slot, per LOD, per part — that's why imported FBX files rebind to the engine's materials with no manual fixing.

6.4 Edit Meshes

6.5 Control Rig

6.6 Blend Shapes

Pick a key on an edit mesh, activate it, sculpt the posed shape at full strength — Skalin DNA Studio maintains the delta. Add Empty Blend Shapes creates zeroed keys ready for sculpting. Restore Blend Shapes from DNA rebuilds every matching shape key — on the originals and the edit meshes — from any compatible DNA file: your source DNA to undo mistakes, or an earlier export.

6.7 Expressions

6.8 Correctives (RBF)

6.9 Skeleton (appears in Edit Mode on an armature)

6.10 Secondary Meshes

6.11 Synchronize

Checkboxes for Head, Body, Blend Shapes, Armatures, Expressions — one button. With head and body both on, it also snaps the neck seams and finishes with the welded-normals pass. Placed directly above Export because that is its place in the workflow.

6.12 Export

7. Workflows

A — Reshape a character (the core loop)

1. Import DNA → Create Edit Meshes → View → Edit. Hide secondaries.
2. Sculpt the skin edit mesh (head+body welded — the neck can't split). Symmetrize when asymmetry creeps in; Conform to Mesh (Skeleton panel, Edit Mode on the armature) keeps bones seated.
3. Secondary Meshes → Conform All pulls the followers into place.
4. Synchronize — LODs conform, seams snap, blend shapes transfer, normals weld. Scrub the View LOD buttons to check every level.
5. Export DNA (new filename) + Export FBX → §9.

B — Edit a blend shape

1. Blend Shapes panel → select and activate the target on the relevant edit mesh.
2. Sculpt what the expression should look like at full strength — you edit the destination, not the delta.
3. Verify live: enable the Control Rig and drive the corresponding board control.
4. Synchronize (Blend Shapes ticked) → export.

C — Customize an expression's rig behavior

1. Enable Control Rig → pose the board until the expression is active.
2. Press Edit next to it in the Expressions list — only the driven bones remain, on the edit rig, in Pose Mode.
3. Repose the bones. Mirror L→R keeps symmetric expressions symmetric.
4. Apply — solved exactly, staged, live. Symmetrize Expression for the twin control. Save the .blend.

D — Edit an RBF corrective pose

1. Correctives → filter → pick solver → click the pose in the list: selection is activation — the limb drives to the exact sample and every other solver resets.
2. Edit Pose → adjust the corrective bones → Apply. Isolate Pose silences everything else if needed.
3. Symmetrize Solver (or Symmetrize All) mirrors exactly. Revert Pose if regretted. Save the .blend.

E — Author wrinkle (animated map) textures

1. Control Rig → WM1/WM2/WM3 — every mask region of that set drives to full (the face looks extreme by design; lips belong to sets 1 and 3 — author them from WM3).
2. Materials → Animated to see your maps blend through the character's masks. Override CM1–3 to iterate; Export Textures ships them.

F — Adjust the skeleton by hand

Edit Mode on the edit armature → move joints → Mirror Selected / Mirror All (never Blender's X-mirror) → Conform to Mesh if meshes changed → Synchronize (Armatures ticked).

8. Saving & Data Safety

The DNA session (the live RigLogic runtime) cannot be stored in a .blend. When you reopen a saved scene and press Enable Control Rig, Skalin DNA Studio revives the session from the DNA paths stored in the scene, then hydrates your staged expression and RBF edits from the .blend — the enable report lists what it restored.

9. Unreal Round-Trip

9.1 Importing the FBX

9.2 What lands automatically

• Material slots rebind by name, per LOD, per part.
• The face attaches at socket None — pelvis → spine_01…03 are synthesized onto the exported head from the body DNA.
• Every part ships in the LOD0 FBX (check the Sections list if something seems missing — it's there with its slot).
• The DNA carries your rig-level work — expressions, RBF poses, neutral transforms, normals, blend shape deltas — in your character's own format generation.

9.3 First use with a new engine version — two ten-second checks

1. Material slot names: compare the engine's slot list on the face skeletal mesh with the exported FBX's materials.
2. Morph names: import one FBX and compare the morph list against the [Skalin DNA Studio] FBX morph names console line printed at export.

10. Troubleshooting

The console (Window → Toggle System Console) narrates everything with [Skalin DNA Studio] lines — it's the first place to look. Validate Setup is the first button to press.

11. If the Bindings Won't Load — Rebuilding Them Yourself

You should never need this section. It applies only if Blender reports that the RigLogic bindings could not be loaded, and the Troubleshooting fixes (§10) — Visual C++ Redistributable, antivirus quarantine — didn't resolve it, or your Blender uses a newer Python than the bundled bindings target.

What rebuilding gives you: bindings compiled on your machine against your exact Python — which always load. Self-built bindings take priority: once the Bindings Folder preference is set, they override the bundled files. Better still, the build script detects an installed Skalin DNA Studio extension and installs its output directly into it — in that case you leave the preference empty and just restart Blender.

11.1 The rebuild procedure

If none of the above apply and the bindings still won't load, rebuild them:

The advanced package for this contains the bundled OpenRigLogic source, build_bindings.bat, and check_prerequisites.ps1.

1. Unpack the package to a permanent folder (e.g. C:\SkalinDNAStudioBindings\). The bindings folder path is stored in Blender's preferences, so don't move it afterwards.

2. Check the toolchain. In PowerShell, in the package folder:

   .\check_prerequisites.ps1            # check only — changes nothing
   .\check_prerequisites.ps1 -Install   # install what's missing (ADMIN window)
   

   If PowerShell blocks the script: Set-ExecutionPolicy -Scope Process -Bypass, then run it again. After an install pass, close the window and open a new PowerShell before re-checking — PATH changes only reach new windows. (Prefer manual installs? Full per-tool tutorial in §11.2.)

3. Build. Double-click build_bindings.bat. It compiles OpenRigLogic and copies four files — dna.py, riglogic.py, _py3dna*.pyd, _py3riglogic*.pyd — into bindings_out\windows\x64\py313 next to the script, printing the full path when it finishes. For a different Blender Python: build_bindings.bat 3.12. Failures are fully logged to build_log.txt.

4. Point the add-on at your build. Preferences → Add-ons → Skalin DNA Studio → set Bindings Folder to the printed path → recheck → restart Blender.

11.2 Installing each build tool by hand — the full tutorial

The script above does all of this for you; this is the same work spelled out. Nothing else is required beyond these four — no Git (the source is bundled), and the Windows SDK comes with the Visual Studio workload.

Visual Studio 2022 Build Tools — the C++ compiler

1. Download Build Tools for Visual Studio 2022 from visualstudio.microsoft.com/downloads (the free Build Tools edition is enough; full Community also works).

2. In the installer, on the Workloads tab, tick "Desktop development with C++". This single checkbox is the whole requirement — it brings MSVC and the Windows SDK. Leave the optional list at its defaults. Install (several GB; the longest step of the whole setup).

3. Confirm in PowerShell:

   & "${env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe" `
     -latest -requires Microsoft.VisualStudio.Component.VC.Tools.x86.x64 -property displayName
   

   Any printed name (e.g. "Visual Studio Build Tools 2022") means the compiler is ready.

Python 3.13 x64 — must match Blender's bundled version

1. Download the Windows installer (64-bit) for the latest 3.13.x from python.org/downloads. The version matters: Blender 5.2 embeds Python 3.13, and the bindings must be built against the same minor version.

2. Run it with the default options — defaults include the py launcher and the development headers, both of which the build needs. "Add python.exe to PATH" is fine but not required.

3. Confirm:

   py -3.13 -c "import struct;print(struct.calcsize('P')*8)"    # must print 64
   py -3.13 -c "import sysconfig,os;print(os.path.isfile(os.path.join(sysconfig.get_paths()['include'],'Python.h')))"   # must print True
   

CMake — the build system

1. winget install -e --id Kitware.CMake, or download the Windows x64 installer from cmake.org/download and choose "Add CMake to the system PATH" during install.
2. Confirm in a new PowerShell window: cmake --version (3.15+).

SWIG 4.x — the binding generator

1. Download the swigwin zip from swig.org/download.html (prebuilt for Windows — nothing to compile).
2. Extract and move the folder so that C:\swigwin\swig.exe exists. That location is found automatically; adding it to PATH is optional.
3. Confirm: C:\swigwin\swig.exe -version.

The winget one-liners (equivalent to the above):

winget install -e --id Microsoft.VisualStudio.2022.BuildTools `
  --override "--quiet --wait --add Microsoft.VisualStudio.Workload.VCTools --includeRecommended"
winget install -e --id Python.Python.3.13
winget install -e --id Kitware.CMake
# SWIG via the swigwin zip as above

After installing anything, open a new PowerShell before verifying — PATH changes never reach already-open windows.

12. Limitations

Stated plainly, so there are no surprises:

• Topology is fixed. Vertex count and order are the DNA link — no adding, deleting, merging or reordering vertices on edit meshes. (Meshes with arbitrary topology can ride along as conformed custom objects, but they are not DNA meshes.)
• Blend shapes exist where the DNA defines them: head (737), cartilage (76), teeth (41), each eye (2). Eyeshell, saliva, eyelashes and eyeEdge carry none — sculpt their neutrals and conform them instead.
• Morphs are LOD0-only, matching every shipped MetaHuman.
• Existing poses and expressions only (current release): every expression and every RBF corrective pose the DNA defines is editable — the complete standard MetaHuman set — but authoring brand-new poses, controls or solvers is not supported yet.
• One character per .blend is the supported workflow.
• Windows x64 only. The bundled prebuilt bindings target Windows x64 and Python 3.13. Linux and macOS are not supported in version 0.9.0 Beta.
• Blender 5.2+, Unreal 5.6–5.8 (see §2 for the full matrices). The supported character source is the in-engine MetaHuman DCC export (UE 5.6+).
• Cross-character content works within a topology generation: edit meshes are deterministic, so meshes and DNA-restores transfer between same-generation MetaHumans; a future Epic topology revision would not correspond vertex-for-vertex.
• Restart discipline: Blender must be restarted after every add-on install or update (compiled bindings cannot hot-reload).

13. FAQ

Can I use a mesh from another Blender file / another character? Yes, within the same MetaHuman topology generation — edit meshes are deterministic (identical vertex count and order), so an appended edit mesh corresponds vertex-for-vertex and works as a conform source or direct shape reference.

Can I undo a mistake in blend shapes or RBF poses? Yes — Restore Blend Shapes from DNA and Restore RBF from DNA rebuild from your source DNA or any earlier export; Revert Pose / Revert All goes back to stock values instantly.

Does the exported DNA replace my source? Never overwrite the source — export to versioned new files. Any export can serve as the source of a future session.

Multiple characters in one file? One character per .blend.

Mac / Linux? Not currently. Version 0.9.0 Beta supports Windows x64 only.

14. Credits & Licensing

Skalin DNA Studio is © Victor Skalin, distributed under the GNU GPL-3.0-or-later — the standard license of the Blender add-on ecosystem. Purchasing grants you the software and its source; the GPL grants you the right to modify and redistribute under the same license. Paid distribution of GPL Blender add-ons is the established norm: what you pay for is the maintained product, updates and support.

Built with: OpenRigLogic (Epic Games, MIT — bundled, incl. prebuilt binaries with license notice), with prior art gratefully studied in MetaReForge (GPL) and Character DNA / Poly Hammer (GPL).

MetaHuman™ and Unreal Engine™ are trademarks of Epic Games, Inc. Skalin Skalin DNA Studio is an independent tool, not affiliated with or endorsed by Epic Games. Use of MetaHuman content is governed by Epic's own license terms.

15. Support

Include your purchase receipt and, for technical issues, the output of Validate Setup plus the [Skalin DNA Studio] console lines — they narrate every operation and are usually the entire diagnosis.

Email: victor@skalin.org — or use the contact section at www.skalin.org.

Skalin DNA Studio — MetaHuman Customizer for Blender. This documentation is a living document and will continue to be updated and improved.