Text to CAD: which tools turn a sentence into a part you can print

What text to CAD means for a printed part

A text-to-CAD tool writes geometry you can measure: OpenSCAD code (GrandpaCAD, CADAM, ModelRift), KCL code behind a feature tree (Zoo), or native features in a CAD app (Adam, Fusion). Because the model is built from numbers, a 20 mm hole is exactly 20 mm in the file. An FDM printer will still print it a little small, which is why you want that number, or a clearance, as a slider you can change after a test print without starting over.

Text-to-3D tools such as Meshy and Tripo do a different job: a triangle mesh that looks right, with no dimensions to edit (Meshy's default unit is even centimetres). That suits a figurine's looks, not a bracket that has to fit a pipe; AI CAD vs mesh generators explains the difference, and Meshy vs Tripo covers the mesh side. For printing, "good" means it builds to the millimetres you state, you can change sizes afterwards, it exports STL or 3MF your slicer opens cleanly, and you don't need to know CAD. STEP matters only if the part continues in Fusion, Onshape or SOLIDWORKS, and if you'd rather learn CAD yourself, see the best CAD software for 3D printing.

How to write a text-to-CAD prompt that prints

These rules are for any tool that builds from the numbers you give it and guesses the rest. We haven't run them through every tool above.

1. Put every critical dimension in millimetres, including the thing it has to fit (a 25 mm pipe, a 6 mm D-shaft, M3 heat-set inserts).
2. Name the fit you want: a press fit, a sliding fit or a loose fit, and the clearance if you know your printer (0.2 to 0.3 mm is a common start).
3. Say how it will print: which face sits on the bed, and that overhangs should stay under about 45 degrees or get a chamfer.
4. Ask for the sizes you'll want to change as named parameters, so you can adjust them after a test print.
5. Name real hardware by its part name. A tool that looks up datasheets can then use the real hole pattern.

A wall bracket for a 25 mm diameter pipe, two halves joined by one M4 bolt with a captive nut.
Wall plate 60 x 40 x 5 mm with two countersunk holes for 4 mm wood screws, 40 mm apart.
0.3 mm clearance around the pipe. Print each half flat on the bed, no supports.
Make pipe diameter, clearance and wall plate thickness parameters.

That brief is close to one of our public examples: the hinged pipe wall bracket below, where changing the pipe diameter re-fits both halves. For more briefs in the same style, see our 25 copy-ready AI CAD prompts.

When Zoo is the better pick

If you're a professional engineer working on complex mechanical parts, use Zoo Design Studio. A full parametric CAD app with Zookeeper, a conversational agent that creates and edits B-rep models with a feature tree; the source is KCL code. Source: Zoo FAQ, checked 2026-11-08 GrandpaCAD has no feature tree or constraints, and complex assemblies take follow-up turns.

Already on Zoo and missing 3MF or sliders? See Zoo Text-to-CAD alternatives.