A 3D-printable OpenSCAD enclosure for Paul Carmody's Speedster bookshelf speakers — designed from scratch with AI, optimized for FDM printing, and engineered to match Carmody's original acoustic spec.
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Designed with AI from day one. The entire enclosure was developed iteratively with an AI agent (GitHub Copilot CLI) working directly in OpenSCAD code. The workflow: describe a feature or problem → the agent writes or modifies the parametric model → export STLs → review in the slicer → iterate. Over 19 sessions, this loop produced the geometry, caught component collisions (tweeter-port overlap, crossover-woofer interference), built a validation suite for faster iteration without regressions, and documented every decision for future work. The full design history — including dead ends and reverted approaches — is preserved in docs/copilot.md. The agent runs in a sandboxed devcontainer with only project files and a scope-limited token, so it has the tools it needs without host access.
Every feature is designed for FDM. The curved enclosure shape looks organic, but every surface was constrained for printability. The front roundover follows a cubic Hermite spline tuned to exactly 45° maximum overhang. Port flares, crossover bosses, and pillar braces all print without supports. A tolerance test print calibrates every fit-critical dimension to your specific printer before committing to the full build.
Acoustic fidelity to Carmody's design. Same drivers, same crossover, same port tuning — the enclosure is the only thing that changed. Internal volume is verified at 5.68L net (Carmody spec: 5.5L). The port dimensions are unchanged. What the original couldn't do: a 20mm baffle roundover for diffraction control, curved walls to break up standing waves, and port entry/exit flares to reduce chuffing. A validation suite runs at every build to verify all clearances and component fits.
| Exploded Front | Exploded Back |
|---|---|
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| Side | Top |
|---|---|
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| Original (Carmody) | SpeedsterAI | |
|---|---|---|
| Internal volume | 5.5 L | 5.68 L net / ~5.35 L effective |
| Port | 1.375" dia × 4.5" long | Same + entry bell / exit chamfer |
| Woofer | Tang Band W4-1720 | Same (heat-set inserts) |
| Tweeter | Fountek NeoCD1.0 | Same (heat-set inserts) |
| Wall | 1/2" MDF | 10mm PETG (5–6 perimeters) |
| Shape | Rectangular box | Curved-back wedge |
| Baffle roundover | None | 20mm Hermite spline |
| Bracing | None | 8× pillar pairs with interlocks |
- Curved-back wedge — quadratic taper from 180×264mm baffle to 118×211mm back over 205mm depth
- Tongue-and-groove split — self-aligning airtight seal at the split plane, no gasket trimming
- 8 bolted pillar pairs — wall reinforcement + shear-resistant alignment via interlock boss/recess
- Internal crossover mounting — HP and LP boards on opposite walls with heat-set insert bosses
- Component envelope validation — 20 analytical assertions + 21 geometric collision checks run at every build
See docs/design.md for the full engineering breakdown.
| Component Fit Front | Component Fit Back |
|---|---|
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- Front half — print baffle-face down
- Back half — print flat back-face down
Designed for the Bambu Lab H2D but any printer with at least a 180 × 264 × 125mm build volume will work. PETG, 0.2mm layers, 5–6 perimeters.
./render.sh # Generate PNG renders (Blender Cycles, photorealistic)
./render.sh --fast # Generate PNG renders (OpenSCAD, faster)
./export.sh # Export print-ready STLs
./validate.sh # Run full validation suite (41 checks)Open speedster-ai.scad in OpenSCAD to explore the parametric model. All dimensions are parameters at the top of the file.
| Doc | Contents |
|---|---|
| Printing & Assembly | Print settings, tolerance calibration, step-by-step assembly, full BOM |
| Design Details | Engineering rationale for every feature — port flares, roundover math, pillar system |
| Development Guide | SCAD usage, render/export/validate pipelines, devcontainer setup |
| Design Analysis | Verification data — volume measurements, clearance margins, collision results |
| AI Design History | Complete 19-session design log — every decision, iteration, and dead end |
speedster-ai/
├── speedster-ai.scad # Parametric OpenSCAD enclosure model
├── component-envelopes.scad # Component clearance envelopes + validation assertions
├── tolerance-test.scad # Printer tolerance calibration print
├── export.sh # STL export pipeline
├── render.sh # Render pipeline (10 PNG views, Blender or --fast OpenSCAD)
├── validate.sh # Validation pipeline (assertions + collision checks)
├── validate.py # Geometric collision detection (trimesh + manifold3d)
├── copilot.sh # Launch Copilot CLI in the devcontainer
├── models/ # Exported STL files
├── renders/ # Generated PNG renders
├── references/ # Component datasheets
└── docs/ # Detailed documentation
├── printing.md # Print settings, assembly, BOM
├── design.md # Engineering design details
├── development.md # Dev guide, pipelines, devcontainer
├── analysis.md # Design verification data
└── copilot.md # AI agent design context
Enclosure design files are provided for personal/hobby use. The Speedster speaker design is by Paul Carmody. Crossover schematic and driver selection are his work.