Serpentine3D

Serpentine3D

An open-source NURBS surface modeller for Linux, Windows & macOS — a Rhino-style freeform workflow with native AI integration.

Download for Linux · Windows · macOS · Website

Serpentine3D (serp3d) is a freeform surface modeller in the spirit of Rhinoceros 3D — BREP/NURBS geometry on the OpenCASCADE kernel, not meshes. It is built for set designers, architects, and industrial designers who want a genuine Rhino-style workflow: a command line that prompts for input, layers, object snaps to a construction plane, STEP/OBJ/FBX interchange, and a dark, focused interface. The whole modelling engine also runs headless, so the same geometry you build by hand can be scripted, batch-processed, or driven by an AI.

Named for the serpentine stone of Zimbabwean Shona sculpture, and for the S-curve at the heart of NURBS geometry.

Why

• No open-source freeform NURBS surface modeller exists. FreeCAD is

parametric solid CAD; Blender is mesh-based. Serpentine3D fills the freeform surface-modelling gap — on Linux, Windows and macOS alike.

• First CAD tool with native AI integration. The bundled MCP server lets

Claude (or any MCP client) see your viewport, create geometry, run any command, and manage the scene.

• Headless-first. The modelling core is fully decoupled from the GUI —

script it (serp3d-batch), import it as a Python library, or drive it over MCP. Repeatable, configurable, light, CI-friendly.

Exact BREP surfaces & solids on OpenCASCADE Zebra & curvature surface analysis

Install

Download

| Platform | Download | Notes | |---|---|---| | Linux | Serpentine3D-x86_64.AppImage | chmod +x and run — nothing to install | | Windows | Serpentine3D-Setup-x86_64.exe | Installer (Inno Setup) | | macOS (Apple Silicon) | Serpentine3D-arm64.dmg | Drag to Applications |

Each download bundles the OpenCASCADE kernel and Python runtime — nothing else to install. The GUI needs a GPU with OpenGL 3.3 drivers, which any normal desktop has; GPU-less VMs and remote-desktop sessions that only expose OpenGL 1.1 get a clear message instead of a viewport. Headless use (serp3d-batch, the MCP server, file conversion) works anywhere.

From source

Requires Python 3.10+.

git clone https://github.com/chisomobanzi/Serpentine3D && cd Serpentine3D
python3 -m venv .venv
.venv/bin/pip install -e .
.venv/bin/serp3d        # launch

The OpenCASCADE kernel installs as pip wheels (cadquery-ocp) — no conda, no system packages. The same install works on Linux, Windows and macOS; the full test suite (360+ tests) passes on all three.

The command line

Everything works Rhino-style: type a command, answer its prompts. Prompts accept typed coordinates (10,5,0, relative @5,0,0) or viewport clicks on the construction plane. Tab completes command names, Up/Down recall history, Enter on an empty line repeats the last command, Escape cancels. As in Rhino, a right-click in the viewport acts as Enter — it runs whatever you've typed, commits a value mid-command, or repeats the last command.

| | Commands | |---|---| | Curves | line polyline curve (interpolated NURBS) circle arc ellipse rectangle helix textobject blendcrv project pull intersect | | Surfaces | extrude revolve loft sweep1 sweep2 planarsrf patch/networksrf offsetsrf unrollsrf | | Solids | box sphere cylinder cone torus filletedge chamferedge (both pick edges directly; fillets chain and take start,end variable radii) shell cap contour booleansplit pushpull | | Deform | twist taper bend flow (curve-to-curve) extend matchcrv | | Booleans | booleanunion booleandifference booleanintersection | | Transform | move copy rotate scale scalenu mirror array | | Edit | join explode trim split offset fillet rebuild pointson/pointsoff (control points, curves and surfaces) delete hide show rename undo redo | | Select | selall selnone selcrv selsrf selsolid sellayer selname sellast invert isolate unisolate | | Organise | group/ungroup lock/unlockall block insert blocklist count bringtofront/sendtoback bringforward/sendbackward (draw order) | | Camera | camera (lens mm, cinema sensors, placement, 2.39/1.85 frame guides) units cplane | | Array | array (grid) arraypolar arraypath (along a curve) | | Analysis | distance length area volume curvature zebra curvaturegraph (combs) draftanalysis printcheck (3D-print readiness: watertight, thin walls, overhangs, size) | | View | top front right perspective 4view/1view zoomextents wireframe shaded ghosted rendered technical grid snap | | Render | material (Matte/Plastic/Metal/Glass/custom PBR — flows into GLB/USD export) rendered | | Layers | layer (new/current/show/hide/rename/weight/linetype) — or use the Layers panel | | Linetypes | linetype — dashed/dotted/hidden/center/… per object or ByLayer (layers carry a linetype too); dashes render in the viewport and in exported layout sheets (PDF/SVG) | | Meshes | heavy OBJ/3DM/FBX props stay native meshes (instant display); meshtobrep / breptomesh convert | | Files | new open save import export (.serp is a zip container with thumbnail + metadata) | | Live | recordhistory — loft/extrude/revolve outputs rebuild when their input curves are edited |

Most commands have Rhino-compatible aliases (l, pl, c, m, co, mi, ...). Command options appear as clickable chips under the prompt (Cap=Yes, BothSides=No, Style=Normal) and can be typed Rhino-style (cap=n) at any moment without losing your place; numeric prompts show a live gold ghost preview of the result while you type. help (or F1) opens a searchable command reference. Arrow keys nudge the selection along the CPlane (Shift ×10, Ctrl ×0.1).

Navigation & shortcuts

• Middle mouse orbit · Shift+Middle pan · Scroll zoom
• F1–F4 top/front/right/perspective · Ctrl+E zoom extents · F7 grid
• Ctrl+Z / Ctrl+Y undo/redo · Ctrl+A select all · Delete delete selection
• Ctrl+S / Ctrl+O / Ctrl+N save/open/new
• Click to select (Shift-click adds, Ctrl-click removes), click empty space

to deselect

• Box selection: drag left-to-right for a window (fully enclosed,

gold box), right-to-left for a crossing (anything touched, white box); Shift adds, Ctrl removes

• Control points: pointson (F10) shows CVs on curves — drag a CV to

edit the curve live; pointsoff (F11) hides them

• Object snaps — end, mid, center, quadrant, intersection,

perpendicular, and nearest-point, each with a distinct cursor marker. Toggle types on the osnap bar under the command line, or in Settings. gridsnap snaps picked points to the grid

• Launch with a file: serp3d model.serp (or any importable format)

Drafting & documentation

Serpentine3D has a full two-space drafting workflow — model in 3D, document in 2D, print to PDF — without leaving the app:

• Layouts (layout): paper-space sheets (A4–A0, Letter, Tabloid or

custom) with tabs at the bottom of the viewport: [Model] [Sheet 1] …

• Detail views (detail): live windows into the model placed on the

sheet — pick two corners, a view direction (top/front/right/…/perspective) and a scale (1:10, 1:50, …). Double-click a detail to enter it, then pan (nav-button drag) and zoom (wheel changes the scale); click outside to exit. detailscale, detailmode, detaillock, detailborder, detaildelete manage the active detail.

• Hidden-line rendering: each detail can be technical (hidden lines

removed), hidden (dashed hidden lines), wireframe or shaded — powered by OCCT's HLR engine, isolated in a worker process so degenerate geometry can never crash the app. The same engine drives the model-space technical display mode.

• make2d: project the current view (or a selection) into real,

editable 2D curves on Make2D visible / Make2D hidden layers.

• Annotations: multiline text, leader, dim / dimradius /

dimdiameter / dimangle, hatch (pick corners or Mode=Region to click inside detail linework), scalebar, titleblock, sheetindex and per-sheet revision tables. Everything on a sheet is selectable — drag to move, grips resize detail frames, Delete removes, annotedit edits — and dimensions picked inside a detail are associative: they re-project when the detail pans or rescales. dimstyle manages named text/arrow styles.

• exportpdf (Ctrl+P): true vector PDF — linework stays crisp at any

zoom; shaded details are embedded as rendered images. Layouts save/load with the .serp file.

The gumball

Select anything and a gumball appears: drag the arrows to move along an axis, the pads to move in a plane, the circles to rotate (Shift snaps to 15°), the square knobs to scale along an axis (Shift = uniform). Alt-drag moves a copy. Escape cancels a drag. gumball toggles it.

Ctrl+Shift-click a face of a solid and the gumball becomes a push/pull handle along the face normal — drag it, or type a distance, to extrude the face outward or carve it inward; the solid rebuilds live and the handle stays on the moved face for repeated pulls. A curved face (a cylinder or cone wall, a sphere) offsets instead — push it to grow or shrink the radius, adjacent faces extending to meet it. Select several faces and one handle offsets them all together, each along its own normal — inflate a shape, or grow a slab from both sides at once.

Ctrl+Shift-click one or more edges and the gumball becomes a fillet handle — drag it outward, or type a radius, to round the edges; every selected edge fillets together at that radius, previewing live. Hold Alt while dragging to chamfer instead of fillet.

Units

units sets the document units (mm/cm/m/in/feet-and-inches) with an optional model rescale. Every prompt then accepts unit input — 3'6", 2' 4 1/2", 30cm, 1.5in — and coordinates support polar entry (`10 a spiral staircase, 3 m tall, 14 steps, 900 mm radius > fillet every edge of the box 2 mm > what's the volume of the hull?

It works with the full command set (the same commands you type), can measure and inspect the scene, and can look at the viewport — it takes a screenshot, checks its own work, and fixes mistakes before answering. Everything it does streams into the panel as it happens, and everything is undoable.

Bring your own Anthropic API key (Settings → Assistant, or the ANTHROPIC_API_KEY environment variable — get one at console.anthropic.com). Usage is billed to your Anthropic account; the assistant never phones home anywhere else, and the key never leaves your machine except to call the API.

MCP server (AI integration)

Prefer driving Serpentine3D from an external agent (Claude Code, Claude Desktop)? The same modelling surface is exposed as MCP tools. Start the app, then register the server with your MCP client:

claude mcp add serpentine3d -- /path/to/.venv/bin/serp3d-mcp

Tools: serp_scene_info, serp_screenshot (returns an image of the viewport), serp_create_curve, serp_create_surface, serp_boolean, serp_transform, serp_select, serp_command (run any command with its interactive inputs), serp_layers, serp_import, serp_export, serp_measure, serp_undo, serp_viewport.

The combination of serp_screenshot and serp_command means an AI assistant can model alongside you: it sees what you see and can operate every tool the command line offers. The bridge is a localhost-only JSON-RPC socket (~/.serpentine3d/rpc.port); set SERP3D_NO_RPC=1 to disable it.

Architecture

serpentine3d/
├── core/          # kernel layer: geometry builders, tessellation,
│                  #   scene graph, layers, selection, undo history
├── commands/      # generator-based interactive commands (Rhino-style
│                  #   prompt protocol, shared by GUI + MCP)
├── ui/            # Qt: GL viewport, command line, panels, dark theme
├── fileio/        # .serp, STEP, 3DM, OBJ, FBX, STL, DXF, SVG, GLB, USD
├── scripting.py   # stable headless Document API (serp3d-batch)
├── mcp_server/    # stdio MCP server -> RPC bridge
├── api.py         # programmatic API over a running session
└── rpc.py         # localhost JSON-RPC bridge

Geometry is exact BREP on OpenCASCADE 7.9 (via the OCP pybind11 bindings); the viewport tessellates on demand with trim-aware isocurve display. Commands are Python generators that yield typed input requests — the same command code serves typed input, viewport clicks, and MCP calls.

Plugins

Drop a .py file into ~/.serpentine3d/plugins/ defining serpentine3d_plugin(ctx), or ship a package with a serpentine3d.plugins entry point — plugins register first-class commands (with prompts, osnaps, undo and MCP support for free) and menu items. See docs/scripting.md.

Development

.venv/bin/pip install -e ".[dev]"
.venv/bin/pytest            # unit tests (geometry, scene, commands, file I/O)

License

MIT

Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: chisomobanzi
• Source: chisomobanzi/Serpentine3D
• License: MIT
• Homepage: https://chisomobanzi.github.io/Serpentine3D/

Install and usage instructions live in the source repository linked above.