Image to CAD: turn a sketch or photo into a printable CAD model
To go from an image to CAD, attach a sketch, photo or drawing to the CAD Agent and type the key sizes in your message. The agent reads the shape from the image and the numbers from your text, writes parametric OpenSCAD, then compares its render with your image and fixes what doesn't match.
- Sketch the part or photograph it straight on, with sizes written on it or a ruler in shot.
- Crop close to the part.
- Attach it with the image button under the chat box, or paste it in. Up to 4 images per message.
- Type what the part is, plus the key sizes in mm.
- Check the brief and the render, then fix one thing per message.
Which images work for image to CAD
The agent builds from geometric shapes in code, so it does best on parts made of boxes, cylinders, holes and chamfers.
| Image | Works well for | Tips |
|---|---|---|
| Hand sketch | Brackets, mounts, plates, jigs | Write the key sizes on it, name the screw size, mark which way is up. |
| Photo of an existing part | Knobs, clips, brackets and spacers you can hold | Shoot straight on with a ruler beside the part. Add a side view. |
| Datasheet or drawing | Hole patterns, PCB outlines, motor faces | Crop to the view with the dimensions you need. |
| Render or product photo | A style to match: ribs, flutes, hex patterns | Say which features to copy and which to ignore. |
Image to CAD, step by step
- Open the CAD Agent and sign in. Simple mode is fine for this.
- Attach your images. Click the image button under the chat box, or copy an image and paste it into the box. PNG, JPEG, GIF and WebP all work, up to 4 per message.
- Write a short message with the numbers. For example: "Bracket like the sketch. 40 mm legs, 20 mm wide, 4 mm thick, M3 holes. All sizes in mm."
- Answer any questions. If the image leaves something open, the agent asks 2–5 quick questions with clickable answers.
- Check the brief and the render. The brief lists the overall size the agent committed to. Compare it with your part.
- Refine one thing at a time. "The slot should be 2 mm wider." See follow-up prompts.
Each image is scaled so its longest side is 1024 px before it's sent. Small writing on a large, uncropped photo can become unreadable, so crop first.
How the agent checks its render against your image
When you attach a reference image, auto-iterate runs after a successful render. The app captures a labelled sheet of the model from several angles (isometric, front, top and right, sometimes with a cut-away section) and sends it to the agent with your original image.
The agent then does one of two things:
- Reports a match and stops.
- Names what's off, for example "the rib in the sketch is twice as tall", edits the code and renders again.
The loop is capped at a few rounds and stops early once the model matches. Each round is another AI call and uses credits. You can switch it off with the Auto-iterate button under the chat box.
On follow-up turns, the picture of your current render takes one of the four image places. Attach up to three new images then.
Sketch to CAD: draw a sketch the agent can read
- Write the numbers that matter. Overall size, hole sizes and the distances between holes. Everything else can be rough.
- Use graph paper if you have it. The grid helps the agent judge proportions you didn't dimension.
- Write clearly, away from the lines. Dark pen on white or graph paper photographs well.
- Name the hardware. "M3", "608 bearing" or "4 mm wood screw" saves a round of questions.
- Mark the bottom. An arrow or "BED" label shows which face should print flat.
- Draw the mating part lightly. An outline of the PCB, bar or bearing the part fits around helps the agent place clearances.
- Cross out rejected ideas. Otherwise the agent may try to include them.
Photo to CAD: photograph a part for the agent
- Shoot straight on. Point the camera square at each face. Angled shots distort sizes.
- Put a ruler in the same plane as the part. A ruler further from the camera than the part makes it look bigger than it is.
- Step back and zoom in. A phone held close with a wide lens bends straight edges. A little distance and zoom keeps them straight.
- Use a plain background and soft light. Hard shadows can look like edges or holes.
- Add the views you need. Front for the outline, side for thickness, top for hole positions.
- Measure with calipers anyway. Type the key sizes in your message. The photo shows the shape and the numbers set the size.
For more photo technique, see photographing objects for 3D scanning.
Datasheets and drawings as references
A cropped screenshot of a datasheet is a good way to match a hole pattern. Still type the numbers you rely on. If the agent misreads a callout, your text wins.
Motor plate that fits the NEMA 17 drawing I attached: 60 × 60 × 5 mm, a 23 mm centre hole for the 22 mm boss, and four 3.4 mm holes on a 31 mm square pattern. Two 5.5 mm wide, 10 mm long mounting slots along one edge. All sizes in mm.
A NEMA 17's holes sit on a 31 mm square, 31 mm apart side to side. Calling it a "31 mm bolt circle" would put them about 9 mm too close together.
Combining text, sketches and photos
- Text + sketch: the sketch carries the shape, the text carries sizes, hardware and material.
- Text + photo + sketch: the photo shows the part you have, the sketch shows what to change.
- Text + two screenshots: one for the part it mates with, one for the look you want.
Limits of image to CAD
Images give shape, not measurements. The agent can see that there are four holes near the corners and a chamfer on top. Exact millimetre values are much more reliable when you type them. Treat the image as the shape and your text as the spec.
- Hidden insides. The agent can't see inside a part. Describe internal pockets and bores in text.
- Perspective. Close-up, angled photos distort proportions. Straight-on shots work best.
- Organic shapes. Faces, animals and sculpted forms don't break down into simple shapes, so the result will look blocky. Use a mesh generator for those.
- Copying designs. Recreate parts you own or have the right to reproduce. A reference photo isn't a licence to copy someone else's design.
When to use image to 3D instead
If the image is a figurine, a pet, a face or a sculpture, you want a mesh, not CAD. The AI 3D Model Generator turns a photo into a printable mesh. For people and pets, Face to 3D and Pet to 3D are tuned for those subjects.
AI tool · free to tryAI 3D Model GeneratorFor organic shapes, upload a photo and get a printable mesh instead of parametric CAD.Open toolCheck yourself
You attach a clear photo of a bracket with a ruler beside it. Where should the exact hole spacing go?
The ruler helps with proportions, but the agent can't measure reliably from pixels. Numbers you type, or write clearly on a sketch, are what it builds to.
Frequently asked questions
Can AI turn a photo into a CAD model?
Yes, for parts made of simple shapes like brackets, mounts, plates and clips. The PrintPal CAD Agent reads the shape from your photo and writes parametric OpenSCAD. It cannot measure reliably from a photo, so put the key sizes in your message or write them on a sketch.
What image formats does the CAD Agent accept?
PNG, JPEG, GIF and WebP, up to 4 images per message, attached with the image button or pasted into the chat box. Each image is scaled so its longest side is 1024 pixels before it is sent, so crop close to the part.
Does my sketch need to be drawn to scale?
No. Write the important dimensions on the sketch or in your message and the agent builds to those numbers. Graph paper and rough proportions still help it place features in the right spots.
Is image to CAD the same as image to 3D?
No. Image to CAD produces an editable parametric model with exact dimensions, which suits functional parts. Image to 3D produces a mesh, which suits organic shapes like figurines, pets and faces. PrintPal's AI 3D Model Generator does image to 3D.
Sources
- NEMA ICS 16 frame size 17 mounting dimensions (31 mm square hole pattern, 22 mm pilot)
- Image handling and auto-iterate behaviour were checked against the CAD Agent itself on 24 October 2026.
Try it with a sketch
Snap a photo of a sketch with the sizes written on it, paste it into the chat box and add one line of text.
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