| name | create-openscad-from-construction-image-en |
| description | Interprets a hand-drawn or photographed construction sketch (image) and generates a valid OpenSCAD (.scad) file from it. Use this skill whenever a user uploads or references a technical drawing, construction sketch, or dimension annotation image and wants a 3D-printable or CAD model as output. Activate for phrases like: "create OpenSCAD from this sketch", "generate .scad from image", "convert drawing to OpenSCAD", "make a CAD file from this photo", "3D model from this construction drawing". Supports dimension labels in English and German (e.g. Länge, Durchmesser, Innensechskant, Aussendurchmesser).
|
| license | CC BY-NC-SA 4.0 |
| compatibility | Requires an AI agent with vision (image input) capability. OpenSCAD optional for local preview. |
| metadata | {"author":"roebi","spec":"https://agentskills.io/specification","based-on-skill":"create-agent-skill-en","based-on-skill-repo":"https://github.com/roebi/agent-skills","based-on-skill-license":"CC BY-NC-SA 4.0"} |
Create OpenSCAD from Construction Image
Converts a hand-drawn or photographed technical/construction sketch into a
parametric OpenSCAD (.scad) file, ready for 3D printing or further CAD work.
When to use this skill
Activate when:
- The user uploads a photo or scan of a hand-drawn technical sketch.
- The user references a construction drawing with labeled dimensions.
- The user asks to convert a drawing, sketch, or annotation image into a 3D model.
- Dimension labels may be in English or German.
Typical trigger phrases:
- "Create OpenSCAD from this sketch / image / drawing / photo"
- "Generate .scad from this construction image"
- "Convert this drawing to OpenSCAD"
- "Make a CAD file / 3D model from this"
- "3D-printable file from this hand drawing"
Skills used (backreferences)
This skill was scaffolded following the create-agent-skill-en workflow and
specification from agentskills.io.
Step-by-step workflow
1. Receive and inspect the image
- Accept the uploaded image (photo, scan, or screenshot of a technical sketch).
- Identify all labeled dimensions, annotations, and geometric shapes visible.
- Note the language of labels (English or German — see translation table below).
2. Extract dimensions and geometry
Read all visible dimension annotations. Common German labels and their meanings:
| German label | English meaning | OpenSCAD parameter example |
|---|
| Länge | Length | length = ...; |
| Breite | Width | width = ...; |
| Höhe | Height | height = ...; |
| Durchmesser / Ø | Diameter | diameter = ...; |
| Radius | Radius | radius = ...; |
| Aussendurchmesser | Outer diameter | outer_diameter = ...; |
| Innendurchmesser | Inner diameter | inner_diameter = ...; |
| Innensechskant | Inner hex (across flats) | inner_hex_width = ...; |
| Wandstärke | Wall thickness | wall_thickness = ...; |
| Tiefe | Depth | depth = ...; |
| Bohrung | Bore / hole | bore_diameter = ...; |
| Schlüsselweite (SW) | Wrench size (hex flats) | hex_across_flats = ...; |
Parse units (mm, cm, m) and convert all values to millimeters in the output.
3. Identify the primary shape
Determine the dominant geometry:
| Shape in sketch | OpenSCAD primitive / pattern |
|---|
| Cylinder / round part | cylinder(h, d, $fn=64) |
| Box / rectangular block | cube([x, y, z]) |
| Hex prism | cylinder(h, d=$fn=6) with adjusted diameter |
| Tube / hollow cylinder | difference() { cylinder(...outer...); cylinder(...inner...) } |
| Hex socket / Innensechskant | difference() { cylinder(outer); cylinder(hex, $fn=6) } |
| Cone / taper | cylinder(h, r1, r2) |
| Sphere | sphere(r) |
For complex multi-feature parts, combine primitives using difference(),
union(), or intersection().
4. Handle hex-across-flats conversion
When a hex is specified as across flats (Schlüsselweite / Innensechskant),
OpenSCAD's cylinder($fn=6) uses the circumradius (across corners).
Convert using:
d_circumradius = across_flats / cos(30)
In OpenSCAD:
// inner_hex_width = across-flats dimension
cylinder(h = length, d = inner_hex_width / cos(30), $fn = 6);
5. Write the OpenSCAD file
Structure the output file as follows:
// <Part name or description>
// Source: hand-drawn construction sketch
// Generated by: create-openscad-from-construction-image-en skill
// --- Parameters (all units: mm) ---
<parameter declarations with comments>
// --- Geometry ---
<OpenSCAD CSG model>
Rules:
- Declare all dimensions as named parameters at the top (easy editing).
- Add a comment on each parameter with its meaning and source label.
- Use
$fn = 64 for smooth cylinders; $fn = 6 for hex prisms.
- Keep geometry readable — one operation per line, proper indentation.
- Add
center = false or center = true explicitly to avoid ambiguity.
6. Output
- Provide the
.scad file as a downloadable file named after the part.
- If the part name is unknown, use
part.scad or derive from the dominant feature.
- Briefly summarize the interpreted dimensions in a table for user verification.
Example: Hex Socket (from real sketch)
Sketch labels read:
- Innensechskant: 8mm
- Aussendurchmesser: 14mm Ø
- Länge: 25mm
Generated OpenSCAD:
// Hex Socket / Innensechskant
// Innensechskant (inner hex across flats): 8mm
// Aussendurchmesser (outer diameter): 14mm
// Länge (length): 25mm
outer_diameter = 14; // mm — Aussendurchmesser
inner_hex_width = 8; // mm — Innensechskant (across flats / Schlüsselweite)
length = 25; // mm — Länge
difference() {
// Outer cylinder
cylinder(h = length, d = outer_diameter, center = false, $fn = 64);
// Inner hexagon bore
// d = across_flats / cos(30) converts SW to circumradius
cylinder(h = length + 1, d = inner_hex_width / cos(30), center = false, $fn = 6);
}
Ambiguity handling
If the sketch is unclear or dimensions are missing:
- State which dimensions were successfully read.
- List what is missing or ambiguous.
- Use a placeholder variable with a comment:
// TODO: verify this dimension.
- Ask the user to confirm before finalizing.
References
