What is vibe-CADing?

You describe what you want or show what you have, an AI writes the model, and you change it by talking to it and dragging its dimensions, not by drawing sketches and constraints yourself. The part on screen is a real parametric solid, so it exports as STEP for any CAD package and as STL for a printer.

Where the term comes from

In early 2025 Andrej Karpathy described vibe coding: writing software by telling an AI what you want and accepting what it writes, judging the result by whether it works rather than by reading every line. Within months engineers were doing the same thing with CAD, asking language models to write part models as code in libraries such as CadQuery, OpenSCAD and build123d, and calling it vibe-CADing.

No single company coined the word, and nobody owns it. This page sets out what we mean by it, because the CAD version of the idea has a problem the coding version does not.

Why CAD is not code

Vibe coding works because software has a cheap, honest check: run it. If the tests pass and the page loads, the vibes were right. A CAD model has no such check on screen. A bracket can look perfect and be 2 mm too short for the bolt pattern it has to meet. You find out when the part is made, which is the most expensive moment to find out anything.

So vibe-CADing needs a ground truth that vibe coding can do without: something physical the model is held to.

The three rules of vibe-CADing

1. Start from evidence when you have it

A sentence is a weak description of a physical object. If the part exists, show it: phone photos, a 3D scan, or the STEP file a supplier sent. Most real CAD work is not inventing new shapes but rebuilding, adapting and replacing parts that already exist, which is AI reverse engineering.

2. Keep every dimension a live parameter

A model is only useful if you can change it. Vibe-CADing should produce a parametric solid, not a frozen mesh: hole diameters, wall thicknesses and lengths you can drag, with the model rebuilding each time. That is what lets you fix a 2 mm miss in two seconds instead of starting over.

3. Make the tool say how close it got

The AI must report its confidence in terms an engineer can act on. From photos that means flagging every dimension it inferred rather than read. From a scan it means a number: the model matches the file within 0.2 mm, say, with any texture or lettering it left out named. A vibe-CADing tool that cannot tell you how wrong it might be is guessing.

Text-to-CAD and part-to-CAD

Most vibe-CADing today is text-to-CAD: describe a new part in words and get a model. It is good for simple new parts such as spacers, enclosures and mounting plates, where your words carry all the information.

Part-to-CAD starts from something physical, and it is where the ground truth comes for free. Image to CAD works from phone photos and one real measurement. STL to CAD works from a scan, and can be checked against it point by point. Both end in the same place: a parametric model you can keep vibe-CADing in words.

What a vibe-CADing session looks like

Here is one in AI Reverse Engineering, starting from a broken part:

1. Show it. Upload phone photos of the part, or its STL or STEP file. Add what a photo cannot show: "aluminium, M8 holes, the slot goes all the way through".
2. Check what it read. The AI lists the part as engineering features (a flange, a boss, four bolt holes, fillets) and builds a solid from them. Fix anything it got wrong.
3. Anchor it. Type one real measurement, say the flange length from your calipers, and every other dimension scales from it. Inferred dimensions are flagged.
4. Steer it. Drag any dimension and the part rebuilds. Or say what is wrong: "the boss is too tall, and the holes should be counterbored".
5. Take it out. Export STEP for your CAD package, STL for a printer, or a Fusion 360 script that rebuilds the part as editable features.
6. Make it. For small plastic parts, the Production package delivers 20 locally made units in Egypt and the GCC.

Where it works, and where it does not yet

Vibe-CADing is strong on the parts most workshops actually need: prismatic and turned parts, brackets, housings, covers, clips, flanges and spares whose geometry is made of planes, cylinders, cones and fillets.

It is weaker on freeform and organic surfaces, on features you cannot see from outside (internal channels, blind cavities), and on tolerances finer than your evidence supports. A phone photo cannot tell 10.00 mm from 10.05 mm. Measure the dimensions that matter, give them to the model, and check the result before you cut metal.

Who vibe-CADing is for

• Maintenance teams replacing parts that broke, where the supplier is gone and there was never a drawing.
• Manufacturers turning a hand-made or 3D-printed sample into a model they can tune before tooling.
• Engineers who know exactly what they want but not the hours of sketching it takes in a CAD package.
• Buyers who need a STEP file to get a real quote from a machine shop, not a photo and a description.