How to design a 3D-printable object with AI
Updated 5 November 2026 · 5 min read
In short
To design a printable object with AI, describe what it has to do, where it'll be used and two or three key dimensions. A parametric CAD tool like objekto produces parts with exact dimensions, checks wall thicknesses and clearances, then you fine-tune and order the print. Mesh generators (text-to-3D) are fine for lookalike figurines and organic shapes, not for parts that have to fit together. On objekto, expect 6 to 25 minutes of design time and 1,900 credits for an object of 2 to 4 parts.
- A good brief fits in four lines: what it does, how it's used, the dimensions that matter, the constraints.
- Meshes for looks; parametric CAD for anything that has to fit, screw together or carry a light load.
- Printability is checked part by part: wall thickness, minimum detail, clearances, maximum size.
- Print price depends on material volume, not on how complex the shape is.
Mesh or parametric CAD: two kinds of 3D AI
AI 3D tools fall into two groups. Mesh generators turn text or an image into a surface made of triangles: quick and impressive for a lookalike figurine or an organic shape, but dimensions are approximate and parts don't fit together. Parametric CAD describes each part with dimensions and operations (extrusions, holes, fillets): it's what engineers use, and it's what objekto's AI writes.
| Mesh generator | Parametric CAD | |
|---|---|---|
| What you get | A triangulated surface (mesh) | Solid parts defined by dimensions |
| Dimensional accuracy | Approximate, scaled | To a tenth of a millimetre |
| Parts that fit together | Rarely | Yes, with calculated clearances |
| Changing a dimension | Regenerate the model | Change the value (slider) |
| Best for | Lookalike figurines, organic decor, avatars | Functional objects, spare parts, mechanisms, stylised figurines at your dimensions |
| Example tools | Meshy, Tripo | objekto, Zoo, Adam |
The difference isn't academic: according to an MIT study published in January 2026, only 26% of AI-stylised 3D models remained structurally viable for everyday use. For an object you'll actually use, the geometry has to be designed for manufacturing from the start.
Writing a good brief
The AI can't guess what you don't tell it. A useful brief answers four questions:
- What's it for? “hold a phone on a handlebar”, “organise cutlery”.
- In what conditions? Indoors or outdoors, sun, water, vibration, daily handling.
- Which dimensions matter? The ones that have to fit or fill a space: “31.8 mm handlebar”, “46 × 38 cm drawer”.
- Any constraints? Preferred material or colour, off-the-shelf parts to build in (screws, a bulb, a tube), what you don't want.
| Vague brief | Useful brief |
|---|---|
| a phone holder | a phone holder for a 31.8 mm bike handlebar, for a phone 75 mm wide, with a soft non-slip band |
| a designer lamp | a lampshade for an E27 lamp holder and LED bulb, 30 cm across, with a wave pattern that diffuses the light, white |
| a drawer organiser | an organiser for a 46 × 38 cm drawer, 5 cm tall, for cutlery, a ladle and scissors |
A photo or sketch always helps, as long as you add at least one real measurement: an image doesn't tell the AI the scale.
Six steps from idea to object
- DescribeWrite the brief, and add a photo, a sketch or a 3D file if you have one. Pick a mode: Design, Invent (three directions for a new idea) or Repair / replace.
- Shape the briefThe assistant asks for whatever's missing (size, use, materials) and shows the price in credits before the design starts.
- DesignThe AI writes the CAD model part by part, generates the files and shows the object in 3D, with an exploded view if it has several parts.
- CheckEach part is checked against the chosen material: walls, details, clearances, maximum size, collisions, stability.
- AdjustChange dimensions with the sliders (free), or ask for a change in the chat.
- OrderChoose the materials: the firm price in US dollars, with VAT and delivery included, appears before you pay. Delivery in France.
What “print-ready” actually means
A model that looks fine on screen isn't necessarily manufacturable. Each material has its own rules, set by the workshop:
- Minimum wall thickness: below it, a wall breaks or doesn't print (0.7 mm in SLS PA12, 1.5 mm once smoothed).
- Smallest detail: the minimum size of embossed detail or text (0.2 mm in PA12, 0.1 mm in ultra-fine resin).
- Clearance between moving parts: the gap that stops two parts printed in place from fusing (0.5 to 0.6 mm in PA12).
- Maximum size: each part has to fit in the machine; beyond that, it gets split.
- Escape holes: a hollow object has to let unused powder or resin out.
- Collisions and stability: parts mustn't intersect, and the object has to stand up.
| Material | Min. wall | Min. detail | Min. clearance | Max. size (mm) | Properties | Price |
|---|---|---|---|---|---|---|
| PA12 white (SLS) | 0.7 mm | 0.2 mm | 0.5 mm | 650 × 550 × 350 | rigid · outdoor | $ |
| PA12 dyed black (SLS) | 0.7 mm | 0.2 mm | 0.5 mm | 320 × 230 × 180 | rigid · outdoor | $ |
| PA12 dyed colours (SLS) | 0.7 mm | 0.2 mm | 0.5 mm | 320 × 230 × 180 | rigid | $ |
| PA12 vapour smoothed (SLS) | 1.5 mm | 0.5 mm | 0.7 mm | 440 × 375 × 345 | rigid · outdoor | $$ |
| PA12 natural grey (MJF) | 0.5 mm | 0.2 mm | 0.6 mm | 380 × 380 × 284 | rigid · outdoor | $ |
| PA12 matte black (MJF) | 0.5 mm | 0.2 mm | 0.6 mm | 360 × 210 × 210 | rigid · outdoor | $ |
| PA12 black vapour smoothed (MJF) | 1.5 mm | 0.5 mm | 0.7 mm | 360 × 210 × 210 | rigid · outdoor | $$ |
| PA12 full colour (MJF) | 1 mm | 0.2 mm | 0.6 mm | 330 × 247 × 190 | rigid | $$$ |
| Flexible TPE (SLS, Shore ≈ 88A) | 0.8 mm | 0.8 mm | 2 mm | 220 × 190 × 190 | flexible · outdoor | $$$ |
| Flexible TPU 95A (FDM)rules to be confirmed | 1.6 mm | 1 mm | 0.8 mm | 250 × 250 × 250 | flexible · outdoor | $ |
| Standard resin (SLA, Somos GP Plus) | 1 mm | 0.4 mm | 0.2 mm | 790 × 790 × 590 | rigid | $$ |
| Clear resin (SLA, Watershed XC)rules to be confirmed | 1 mm | 0.4 mm | 0.2 mm | 790 × 790 × 590 | rigid | $$ |
| Black resin (SLA, Watershed Black)rules to be confirmed | 1 mm | 0.4 mm | 0.2 mm | 790 × 790 × 590 | rigid | $$ |
| Ultra-fine resin (MJP Visijet)rules to be confirmed | 1 mm | 0.1 mm | 0.2 mm | 298 × 203 × 185 | rigid | $$$ |
| Cast brass (lost wax) | 0.6 mm | 0.4 mm | 0.3 mm | 100 × 89 × 89 | rigid · outdoor | $$$$ |
| PETG (FDM) | 0.5 mm | 0.5 mm | 0.5 mm | 300 × 300 × 300 | rigid · outdoor | $ |
| PLA (FDM) | 0.5 mm | 0.5 mm | 0.5 mm | 300 × 300 × 300 | rigid | $ |
Costs and lead times
On objekto, design is paid in credits according to the number of unique parts: 950 credits (S, 1 part), 1,900 credits (M, 2–4 parts), 3,400 credits (L, 5–8 parts), 5,200 credits (XL, 9–12 parts). Each chat message usually costs 20–60 credits; sliders, print quotes, renders and the assembly guide are free. You get 2,000 credits free at signup, enough to design a first object.
Printing is paid separately, in US dollars. Generation time, measured on real jobs over the last 45 days (median, then the usual range, queue included): S 11 min (5–31), M 28 min (21–49), L 57 min (36–67), XL 73 min (53–94), by size (S = 1 part to XL = the most parts). Slider changes take a few seconds; the time left is shown during the generation. Manufacturing and delivery take 1 to 3 weeks (an estimate).
| Object | Printed parts | Materials | Design | Delivered print |
|---|---|---|---|---|
| Vulpe, a low-poly fox figurine | 1 | SLA resin | S · 950 credits | $40.90 |
| Toy Racing Car "Comète", 100% 3D printed | 5 | PETG | L · 3,400 credits | $80.90 |
| Vintage rolling scooter figurine | 5 | PETG + TPU 95A | L · 3,400 credits | $100.90 |
The most common mistakes
- No dimensions: the AI falls back on default sizes that won't match your space.
- Trying to print everything: springs, blades, metal shafts and magnets are bought in; the AI lists them as hardware.
- Text that's too fine: under 5 mm tall and 0.5 mm deep, it becomes unreadable.
- Forgetting the environment: heat, sun, water and food contact all change which material to use.
- One giant part: anything bigger than the machine has to be split, so plan for it in the brief.
Frequently asked questions
Do I need a 3D printer?
No. objekto designs the object, then has it made by an industrial 3D-printing workshop, which ships it to you.
Can the AI design from a photo?
Yes, if you add at least one real measurement. The photo is a shape reference; the dimensions come from your measurements.
Can I get the 3D file?
Yes on paid plans: STL, 3MF and STEP, plus the parametric source code on Pro and Studio. See pricing.
What is parametric CAD?
A way of describing an object with dimensions and operations rather than a surface. Changing one dimension recalculates the whole part, so you can make precise adjustments without redrawing it.