How to describe a part so the AI models it right the first time
SpeakCAD understands ordinary language, but the more concrete your description, the fewer rounds you need. This is the structure that works, with copy-paste templates.The four things every prompt should have
- What it is and what it does. "A wall bracket that holds a curtain rod." The purpose tells the AI which design rules apply.
- The dimensions that matter. Mating dimensions first (rod diameter, screw size, hole spacing), then the envelope.
- How it attaches or fits. Screws, snap, press fit, sliding, magnets. Name the fit and the AI applies the right clearance.
- Constraints and style. Wall thickness, rounded edges, material, orientation, "keep it minimal".
A template
Example: "A bracket for a 32 mm curtain rod. The rod sits 20 mm from the wall. Two countersunk M4 screw holes 40 mm apart. About 50 x 40 x 60 mm. 4 mm walls, rounded edges, and a small lip so the rod cannot roll out."
Units and numbers
Use millimetres. Decimals are fine (6.35 mm hex). If you only know one dimension, give it and say "proportional" for the rest; the AI will pick and report sensible values.
Photos and files
Attach a photo when the shape is hard to describe; still write the key numbers, because a photo has no scale. Attach an STL/3MF when the new part must fit an existing one (a lid for a box you already printed). Attach a .scad file to continue an existing design.
Iterating
Be specific about the change and the amount: "make the slot 2 mm wider" beats "the slot is too small". If a test print is off, quote the measured gap. Small fixes re-download free; the AI flags a "major" change only when the design genuinely changes.
Things that help
- Say "single part" or "two parts side by side" when it matters.
- Mention the printer bed if it is smaller than 220 x 220 mm.
- Ask for parameters you may want to tweak later ("make the height a parameter").
- Ask "what did you assume?" to surface defaults you did not specify.
Things to avoid
- Vague adjectives without numbers ("big", "thick").
- Organic or sculptural shapes: SpeakCAD is a CAD engine, not a sculptor.
- Asking for many unrelated parts in one message; one part per model keeps edits clean.