- Builds to your millimetres3
- Change sizes without re-prompting2
- Sculpted shapes2
- Slicer-ready export2
- No CAD skills needed2
- Multi-colour 3MF1
- STEP export1
- Free plan includes downloads1
The ranking on this site is computed from eight yes-or-no questions about each tool, answered from its own documentation or a named third party, and weighted for people who 3D print. Here are the questions, the weights, every score, and what happens to the order if you weigh things differently.
How this guide works
- Made by the GrandpaCAD team. It's our product, so our name is under every headline.
- We set the criteria and score every tool ourselves, GrandpaCAD included. Eight criteria, published weights, and a source and date on every rival fact.
- No sponsors or affiliate links. No other company pays for a place here.
The eight criteria and their weights
| Criterion | Question | Weight |
|---|---|---|
| Builds to your millimetres | If you type a size, does the file come out at that size, as a solid, without manual rescaling? | 3 |
| Change sizes without re-prompting | Can you change a dimension after the first result (sliders, parameters or a feature tree) instead of generating again? | 2 |
| Sculpted shapes | Can it make figurines, creatures and other organic shapes? | 2 |
| Slicer-ready export | Does it export STL or 3MF that a slicer opens without a separate repair step? | 2 |
| No CAD skills needed | Can someone who has never used CAD get a part by describing it or showing a picture? | 2 |
| Multi-colour 3MF | Does it export a 3MF already split into filament colours for an AMS-style printer? | 1 |
| STEP export | Can you export a STEP file? | 1 |
| Free plan includes downloads | Can a free account download the files it makes? | 1 |
Each answer is one of Yes (1), Partly (0.5), No (0), Not listed (0). A tool's score is the sum of weight times credit, out of 14. "Not listed" scores zero on purpose: if a vendor doesn't document a feature, a maker can't count on it. If a vendor shows us it does, we change the mark and the date.
Why these weights: exact millimetres matter most because a part that doesn't fit is a wasted print. Editing afterwards, sculpted shapes, a clean STL or 3MF, and not needing CAD skills are what separate a useful maker tool from a demo. Colour, STEP and free downloads matter a lot to some makers and not at all to others, so they count once. We picked these weights, and they suit a tool that does both parts and sculpts, like ours. That's why every score is below and the sensitivity table shows what other weights would do.
Every tool's score
Computed at build time from the marks below; nobody types a score in. Each mark links to its source.
YesPartlyNoNot listed
If you weigh it differently
The same marks under other weights. GrandpaCAD's place changes; here's how.
- Rank 1: GrandpaCADour pick15 out of 16
- Rank 2: BuildCAD AI13 out of 16
- Rank 3: Zoo Design Studiofor pro engineering12 out of 16
- Rank 4, tied: Adam10 out of 16
- Rank 4, tied: CADAM10 out of 16
- Rank 1: BuildCAD AI11 out of 11
- Rank 2, tied: CADAM10 out of 11
- Rank 2, tied: GrandpaCADour pick10 out of 11
- Rank 2, tied: Zoo Design Studiofor pro engineering10 out of 11
- Rank 5, tied: Adam8 out of 11
- Rank 1, tied: BuildCAD AI13 out of 16
- Rank 1, tied: GrandpaCADour pick13 out of 16
- Rank 3, tied: CADAM12 out of 16
- Rank 3, tied: Zoo Design Studiofor pro engineering12 out of 16
- Rank 5: Meshy9 out of 16
Bars share one scale, up to 16 points, so the panels compare directly. The tick on each track is that panel's maximum. Facts checked 8 Nov 2026.
The same results as a table
| Change | Top three (score) | GrandpaCAD's place |
|---|---|---|
| STEP weighted 3 instead of 1 | GrandpaCAD 15 · BuildCAD AI 13 · Zoo Design Studio 12 | 1st |
| Sculpted shapes and multi-colour weighted 0 (functional parts only) | BuildCAD AI 11 · CADAM 10 · GrandpaCAD 10 | tied 2nd |
| Free downloads weighted 3 instead of 1 | BuildCAD AI 13 · GrandpaCAD 13 · CADAM 12 | tied 1st |
One set of weights for every page
Every ranked list on this site, from the home page to the figurine and alternatives pages, sorts on the weights in the table above. A maker who prints a figurine today often prints a bracket tomorrow, and a ranking that changes order from page to page is harder to check than one that doesn't. With one set, a tool's place on any page is its place in the full score table, minus the tools that page doesn't list.
The sensitivity charts above stay, so you can see what other weights would do to the order.
How the category picks are made
"Best overall" is the top score, checked by code: the build fails if the data and the stated pick disagree. The other categories are our judgement. Each has hard requirements (for "Best for professional engineers and complex mechanical parts", the pick must build to dimensions, edit afterwards and export STEP), and the build fails if a pick doesn't meet them. A judgement pick isn't always the top score for that job: for "Best for functional parts that have to fit", BuildCAD AI scores 11 on parts-only weights against GrandpaCAD's 10, as the sensitivity charts show. We recommend GrandpaCAD in every category but one, which goes to Zoo Design Studio; those are the only two tools we name as a pick anywhere on the site, and the build enforces that too.
- Best overall for 3D-printing makers: GrandpaCAD. Highest score on our published weights, and we think it's the easiest AI CAD: a plain chat that still does advanced work.
- Easiest to start with: GrandpaCAD. It's a chat, the interface everyone already knows, and the agent asks a short question when an answer would change the part.
- Best for functional parts that have to fit: GrandpaCAD. Real millimetres with a slider per dimension, threads, press fits and clearances, and 3MF, STL or STEP files. For professional engineering: Zoo Design Studio.
- Best for sculpted and multi-colour prints: GrandpaCAD. Sculpted figurines in a 3MF painted in four filaments, fused with an exact part when the print needs a base.
- Best for a photo or sketch to a print: GrandpaCAD. A photo becomes a sculpted figurine and a sketch becomes a measured part, refined in the same chat.
- Best for professional engineers and complex mechanical parts: Zoo Design Studio. A full parametric CAD app around its Zookeeper agent: a feature tree, sketches and human-readable KCL code, exact B-rep solids and STEP export, on desktop and in the browser.
Sources and dates
Every rival fact on this site comes from the vendor's own pricing page, docs, help centre or repository, or from a named third party (engineering.com, Wevolver, CostBench, Smith3D, Hacker News threads), and carries the URL and the date we read it. Where a vendor's site blocked our fetcher (Tripo's pricing, Autodesk), we say the fact is unverified. Where sources disagree (MakerLab's multi-colour output), we say that too.
GrandpaCAD facts come from grandpacad.com's live pages (pricing, the 2.0 page, the ChatGPT and Claude page, the terms). Where our own pages disagree with each other, we use the conservative version: for example, we only count OpenSCAD as a live engine, and we don't quote usage numbers we can't check.
All facts on this version were checked on 2026-11-08. Prices are in US dollars unless marked, and exclude tax unless the vendor includes it.
What we haven't done yet
We haven't run the same prompts through every tool, and we haven't printed or measured their output. So there are no pass or fail results, print photos or caliper readings for rival tools on this site, and none for GrandpaCAD beyond its public example models. When we run a test, we'll publish the prompts, printer, filament, slicer settings and every result, including the ones where GrandpaCAD fails, and bump the method version.
The test parts we plan to use, from easy to hard: a 20 mm calibration cube, an M3 counterbored plate, a 2x1 Gridfinity bin, a 608 bearing holder, a print-in-place hinge with a 0.3 mm gap, an Arduino Uno enclosure with a lid, a wall hook, a cable clip for a 6 mm cable, an embossed nameplate and a small figurine.
Editorial and corrections policy
- Which tools we list. AI tools that make a model you can 3D print from a prompt, photo or sketch, plus the classic CAD programs makers compare them with. A tool is ranked when we can mark all eight criteria from its own documentation; otherwise it's listed as checked but not ranked, with the reason. We drop a tool when it shuts down or stops offering a printable export.
- Money. No vendor pays for a place or a mark, and there are no affiliate links. The only commercial interest is our own: we make GrandpaCAD, which is why every page carries our byline.
- Corrections. Email corrections@bestaicad.com with the page, the fact and a source. Vendors are welcome to correct their own entries. We fix confirmed errors, change the source date, and log the fix under Changes below.
- Dates. "Published" is when a page first went up. "Updated" changes only when the page's content changes. "Last checked" is when we last re-read the sources behind the facts.
Changes
- First version published (method version 2), with facts checked on 2026-11-08. Every ranked list sorts on one set of weights. GrandpaCAD is our pick in every category except professional engineering and complex mechanical parts, which goes to Zoo Design Studio.
When Zoo is the better pick
For professional engineers working on complex mechanical parts, Zoo Design Studio is the better pick: a full parametric CAD app with a feature tree and editable KCL code around its AI agent. GrandpaCAD has no feature tree or constraints. Its other limits are on our GrandpaCAD page, and the sensitivity table above shows the weightings where GrandpaCAD isn't first.