AgentModelSheet-metal CAD with an AI agent: OpenSCAD vs SolidCraft
Sheet-metal parts need two deliverables: the folded part and a flat pattern a laser or punch can cut, with bend allowances computed from the material thickness, bend radius and K-factor.
We asked Claude Opus 5.5, working as an agent, for six parts: an angle bracket, a Z-bracket, a cable channel with return lips, an electronics tray with corner reliefs, a wall shelf and a NEMA 17 motor mount. Each part was built twice, once in plain OpenSCAD and once in SolidCraft, a B-rep CAD tool with sheet-metal commands. The output is a folded STL, a flat-pattern DXF and, from SolidCraft, a STEP file and a bend table.
Key findings
- Both tools built all six parts, and the judge scored every one 4 out of 5 for overall match and for manufacturability.
- Flat-pattern sizes match the bend-allowance math on every part. The only folded-size deviation, 1.3 % on the Z-bracket's offset, appears in both tools.
- Speed is similar: 72 s median per part in OpenSCAD and 78 s in SolidCraft. OpenSCAD used fewer tokens (388k vs 555k over six parts).
- The difference is in the output. OpenSCAD computes the flat pattern from formulas and has no bend lines. SolidCraft unfolds the real solid and adds a STEP file and a bend table, which is what a fabricator expects.
Scoreboard
| Contender | Mode | Built | Mean score | Median time | Cost / tokens |
|---|---|---|---|---|---|
| Opus 5.5 agent · OpenSCAD | Agent (self-checking) | 6/6 | 4.00 | 72 s | 388k tokens |
| Opus 5.5 agent · SolidCraft | Agent (self-checking) | 6/6 | 4.00 | 78 s | 555k tokens |
- Opus 5.5 agent · OpenSCAD
- Opus 5.5 agent · SolidCraft
Score by part
| Part | Opus 5.5 agent OpenSCAD | Opus 5.5 agent SolidCraft |
|---|---|---|
| 90° angle bracket | 4 | 4 |
| Z offset bracket | 4 | 4 |
| NEMA 17 motor L-mount | 4 | 4 |
| Four-wall electronics tray | 4 | 4 |
| Small wall shelf | 4 | 4 |
| U-channel cable tray with return lips | 4 | 4 |
Ringed scores are the best on that part. Click a part to jump to its renders.
Results
#90° angle bracket
A sheet-metal 90° angle bracket in 1.5 mm steel: two legs, each 40 mm measured to the outside of the bend, 30 mm wide, inside bend radius 1.5 mm, K-factor 0.44. Two Ø5.5 mm holes in each leg, 15 mm from the bend's outside face and 8 mm in from each side edge. Give me the folded part and its flat pattern.
Expected size: 40 × 30 × 40 mm
Opus 5.5 agent OpenSCAD4
4 views ↗
- Judge
- fidelity 4 · manufacturability 4
- Size
- 40 × 30 × 40 mm (0.0% off spec)
- Flat
- 77.39 × 30 mm
- Time
- 64 s · 64k tokens
Accurate folded geometry and flat pattern. Hole placements, bend radius, and flanges match prompt specifications. Highly manufacturable standard bracket.
Opus 5.5 agent SolidCraft4
4 views ↗
- Judge
- fidelity 4 · manufacturability 4
- Size
- 40 × 30 × 40 mm (0.0% off spec)
- Flat
- 77.39 × 30 mm
- Time
- 71 s · 93k tokens
Accurate folded geometry and flat pattern. Hole placements, bend specifications, and dimensions match the prompt. Highly manufacturable with holes clear of the bend.
#Z offset bracket
A sheet-metal Z bracket (offset bracket) in 2 mm aluminum: 30 mm wide, a 20 mm offset between the two parallel flanges measured outside to outside, each flange 25 mm long from the outside of its bend, inside bend radius 2 mm, K-factor 0.44. One Ø4.5 mm hole centred in each flange. Folded part plus flat pattern.
Expected size: 50 × 30 × 20 mm
Opus 5.5 agent OpenSCAD4
4 views ↗
- Judge
- fidelity 4 · manufacturability 4
- Size
- 48 × 30 × 20 mm (1.3% off spec)
- Flat
- 63.05 × 30 mm
- Time
- 68 s · 63k tokens
Accurate Z bracket with correct flanges, offset, and centered holes. Flat pattern matches folded geometry. Manufacturable.
Opus 5.5 agent SolidCraft4
4 views ↗
- Judge
- fidelity 4 · manufacturability 4
- Size
- 48 × 30 × 20 mm (1.3% off spec)
- Flat
- 63.05 × 30 mm
- Time
- 1.6 min · 95k tokens
Accurate Z-bracket with correct flanges, offset, and centered holes. Flat pattern is correct and manufacturable.
#NEMA 17 motor L-mount
A bent sheet-metal L mount for a NEMA 17 stepper, 2 mm steel, inside bend radius 2 mm, K-factor 0.44. The upright face is 50 × 50 mm with a Ø22.5 mm centre bore and four Ø3.4 mm holes on a 31 mm square pattern, centred on the face. The base is 50 wide × 40 deep with two 5.5 mm wide × 12 mm long slots running front-to-back for M5 screws. Folded part plus flat pattern.
Expected size: 50 × 40 × 50 mm
Opus 5.5 agent OpenSCAD4
4 views ↗
- Judge
- fidelity 4 · manufacturability 4
- Size
- 50 × 40 × 50 mm (0.0% off spec)
- Flat
- 50 × 86.52 mm
- Time
- 72 s · 62k tokens
Accurate L-mount with correct hole patterns and slots. Flat pattern matches folded geometry perfectly. Highly manufacturable.
Opus 5.5 agent SolidCraft4
4 views ↗
- Judge
- fidelity 4 · manufacturability 4
- Size
- 50 × 40 × 50 mm (0.0% off spec)
- Flat
- 50 × 86.52 mm
- Time
- 78 s · 91k tokens
Accurate geometry, correct slot orientation, and valid flat pattern. Highly manufacturable.
#Four-wall electronics tray
A sheet-metal electronics tray from 1 mm aluminum: 120 × 80 mm base, walls 20 mm tall folded up on all four sides, inside bend radius 1 mm, K-factor 0.44, round corner reliefs so it folds cleanly. Four Ø3.2 mm mounting holes in the base on a 100 × 60 mm rectangle, centred. Folded part plus flat pattern.
Expected size: 120 × 80 × 20 mm
Opus 5.5 agent OpenSCAD4
4 views ↗
- Judge
- fidelity 4 · manufacturability 4
- Size
- 120 × 80 × 20 mm (0.0% off spec)
- Flat
- 156.52 × 116.52 mm
- Time
- 2.1 min · 73k tokens
Accurate tray with correct walls, holes, and round corner reliefs. Flat pattern matches the folded geometry perfectly.
Opus 5.5 agent SolidCraft4
4 views ↗
- Judge
- fidelity 4 · manufacturability 4
- Size
- 120 × 80 × 20 mm (0.0% off spec)
- Flat
- 156.52 × 116.52 mm
- Time
- 1.6 min · 91k tokens
Accurate geometry matching the prompt. Flanges, round reliefs, and holes are correctly placed. Highly manufacturable.
#Small wall shelf
A small sheet-metal wall shelf in 1.5 mm steel, inside bend radius 1.5 mm, K-factor 0.44: a 300 mm wide × 120 mm deep shelf, a 50 mm tall back flange folded up that screws to the wall through two Ø5 mm holes 40 mm in from each end and 35 mm above the shelf surface, and a 10 mm lip folded up along the front edge so things don't roll off. Folded part plus flat pattern.
Expected size: 300 × 120 × 50 mm
Opus 5.5 agent OpenSCAD4
4 views ↗
- Judge
- fidelity 4 · manufacturability 4
- Size
- 300 × 120 × 50 mm (0.0% off spec)
- Flat
- 300 × 174.79 mm
- Time
- 75 s · 64k tokens
Accurate sheet metal part. Both flanges fold up correctly, holes are properly placed on the back flange, and the flat pattern matches the folded geometry perfectly.
Opus 5.5 agent SolidCraft4
4 views ↗
- Judge
- fidelity 4 · manufacturability 4
- Size
- 300 × 120 × 50 mm (0.0% off spec)
- Flat
- 300 × 174.79 mm
- Time
- 78 s · 93k tokens
Accurate shelf with correct flanges, bends, and holes. Flat pattern matches folded geometry.
#U-channel cable tray with return lips
An under-desk cable tray: a sheet-metal U-channel 250 mm long in 1.2 mm steel, 42 mm wide and 30 mm tall measured outside, inside bend radius 1.2 mm, K-factor 0.44, with 8 mm return lips folded inward along both top edges. A row of six Ø5 mm screw holes down the centre of the base, 40 mm apart and centred along the length. Folded part plus flat pattern.
Expected size: 250 × 42 × 30 mm
Opus 5.5 agent OpenSCAD4
4 views ↗
- Judge
- fidelity 4 · manufacturability 4
- Size
- 250 × 42 × 30 mm (0.0% off spec)
- Flat
- 250 × 109.66 mm
- Time
- 52 s · 61k tokens
Part and flat pattern accurately reflect all prompt requirements. Proportions, return lips, and hole spacing are correct. Manufacturability is solid with appropriate bend radii.
Opus 5.5 agent SolidCraft4
4 views ↗
- Judge
- fidelity 4 · manufacturability 4
- Size
- 250 × 42 × 30 mm (0.0% off spec)
- Flat
- 250 × 109.66 mm
- Time
- 72 s · 92k tokens
Accurate U-channel with inward return lips and centered holes. Flat pattern is correct and highly manufacturable.
How this was run
Each prompt gives material thickness, inside bend radius and K-factor, so flat-pattern sizes can be checked against the bend-allowance formula.
Both arms are Claude Opus 5.5 as an agent with a shell, free to render, measure and revise. Only the CAD tool changes. Time is the whole agent session.
Gemini 3.1 Pro scores the same four-view render of each folded part, plus the flat pattern, 1–5 for overall match, fidelity and manufacturability.
Every model file is linked under its render. Open a .scad file in OpenSCAD or a .step file in any CAD tool to inspect the geometry yourself.