# print3d
A [Hermes Agent](https://github.com/NousResearch/hermes-agent) plugin that turns
an idea, a photo of an object, or the shop listing of something you would
otherwise buy into a sliced print project for a **Bambu Lab X2D or P2S (0.4 mm
nozzle, via Bambu Studio)** or an **Elegoo Centauri Carbon or Centauri Carbon 2
(0.4 mm nozzle, via ElegooSlicer)**. One part or several, in one colour or two,
with fits measured against your own printer, a 3D view to turn the result around
in, and a print sheet to hand on. It also works with Claude Code, Codex, Cursor
and Gemini CLI.
*A museum photo of a clothes peg, and no CAD: scaled from the ruler beside it,
measured with evidence, modelled, checked against the photo, sliced.
[Full-resolution video](docs/workflow.mp4) · [stills](docs/workflow/) ·
[the benchmark](#benchmark-a-clothes-peg-from-a-museum-photo).*
The agent writes a Blender script that builds the part. print3d runs it, checks
the mesh, slices it with your printer's slicer, and tells the agent
what to fix. The agent repeats until every check passes, then hands you the
`.3mf` to open in the slicer and print from there.
```
idea -> Blender script -> mesh -> checks -> slice -> .3mf -> you print from the slicer
^ |
+---- fix the script --+
```
Nothing here talks to the printer.
## Install in Hermes
You need [Blender](https://www.blender.org/download/) 4.2+,
[ElegooSlicer](https://www.elegoo.com/pages/elegoo-slicer) or
[Bambu Studio](https://bambulab.com/en/download/studio) and
[uv](https://docs.astral.sh/uv/) on the same machine as Hermes. Then:
```bash
hermes plugins install mfranzon/print3d --enable
```
or, in the Hermes desktop app, open
`hermes://plugin/install?repo=mfranzon/print3d&enable=1`.
The plugin brings two things:
- **The print3d tools**, as an MCP server: `make`, `measure_*`, `likeness`,
`handoff`, `view` and the rest. Hermes starts it from the plugin's own copy
through `uvx`; the first start takes a moment while uv builds it.
- **The print3d skill**, the workflow the agent follows from brief to hand-off.
You don't need `print3d setup` for this: the plugin registers the server
itself, so there is no Hermes config to edit.
Start a new session afterwards. `hermes plugins update print3d` updates both;
`hermes plugins remove print3d` removes both.
Explicit `BLENDER_BIN`, `ELEGOO_SLICER_BIN` and `BAMBU_STUDIO_BIN` paths take
precedence, followed by executables on `PATH`. On macOS, Blender and the
slicers are also found in `/Applications`. On Windows, print3d checks the
Program Files directories for `Blender Foundation/Blender <version>/blender.exe`,
`ElegooSlicer/elegoo-slicer.exe` and `Bambu Studio/bambu-studio.exe`, preferring
newer Blender version folders within each directory. Custom and portable
installations can use the environment variables above. Jobs go to
`~/print3d/jobs`, or `$PRINT3D_JOBS`. You only need the slicer of the printer
you [choose](#your-printer): Bambu Studio for the Bambu Lab printers,
ElegooSlicer for the Centauri Carbons.
Hermes looks for Blender 4.2+ before it installs the plugin, and refuses the
install when there is none. It checks the usual places: `/Applications` and
Steam on macOS; `PATH`, flatpak, snap, Steam, `~/blender-*/blender` and
`/opt/blender*/blender` on Linux; the uninstall registry
and Program Files on Windows. If Blender is uninstalled later, Hermes hides the
print3d tools and asks you to install it again. A Blender it cannot find there,
such as a tarball unpacked outside those locations and reached only through
`BLENDER_BIN`, needs the
[setup route](#other-agents) instead, which registers the server in Hermes's
`config.yaml` without the check.
## Use it in Hermes
Ask for a part:
```text
a 40mm nameplate that says MARCO
recreate the knob in ~/Desktop/knob.jpg, it sits on a 6 mm D-shaft
a box for business cards with a sliding lid, ACME inlaid in black
replace this instead of buying it: https://shop.example/wall-hook
```
Hermes models the part, runs the checks, fixes what they flag, and slices. Tools
that make pictures (the plate preview, the likeness overlays, the coordinate grid
over a photo) return them as images, so the agent sees what it built.
Every run also writes `jobs/<slug>/view.html`, the part in 3D: drag to rotate,
scroll to zoom, hide parts, pull them apart with the Explode slider, and
**Measure** between two points on the surface (a click near a corner snaps to it). In the
**Hermes desktop app** the agent opens it in the preview pane beside the chat,
so you can turn the part around while you ask for changes. In the TUI or a
messaging app, you get the images and the path to open in a browser. The page is
one self-contained file; three.js loads from a CDN, so it needs a connection the
first time.
When the job is green, Hermes reports time, grams and layers and gives you the
project file, `jobs/<slug>/slice/<slug>.3mf`. Open that one in Studio: the
`.gcode.3mf` beside it is the sliced job and won't open in the Prepare tab. Ask
for a hand-off and you also get a [print sheet](#hand-it-off).
## Your printer
print3d slices for the X2D unless you choose another printer it has presets for:
| Printer | Key | Nozzles | Build volume |
| --- | --- | --- | --- |
| Bambu Lab X2D | `x2d-0.4` (default) | two, 0.4 mm | 256 × 256 × 261 mm |
| Bambu Lab P2S | `p2s-0.4` | one, 0.4 mm | 256 × 256 × 256 mm |
| Elegoo Centauri Carbon | `elegoo-cc-0.4` | one, 0.4 mm | 256 × 256 × 256 mm |
| Elegoo Centauri Carbon 2 | `elegoo-cc2-0.4` | one, 0.4 mm | 256 × 256 × 256 mm |
The Bambu Lab printers slice in Bambu Studio, the Centauri Carbons in
ElegooSlicer; print3d runs the one that reads the chosen printer's presets.
```bash
print3d printer p2s-0.4 # saved in ~/print3d/printer.json
```
In Hermes, ask the agent to switch; it uses the `printer` tool. `$PRINT3D_PRINTER`
overrides the saved choice for one run. The build volume check, the colour
advice and the print sheet read the chosen printer's presets, and every report
names the printer it sliced for. A choice that names a printer print3d has no
presets for is an error, never a quiet fall back to the X2D.
On the P2S every colour after the first is a filament change through the AMS,
with a purge each time and a prime tower beside the part, so a multi-colour
part takes more time and filament than on the X2D.
## What it runs and reaches
- **Local programs:** Blender, to run the model scripts the agent writes and to
render, and Bambu Studio's command line, to slice. Both run as child processes
on your machine, headless. A model script is Python: Blender runs it with your
user's permissions, outside Hermes's terminal sandbox. The plugin marks its
server untrusted, so Hermes asks before any tool that runs a script or writes
files (`make`, `fit_coupon`, `handoff`, `measure_*`, `fits` with values);
the read-only tools run without asking.
- **Files:** jobs are written to `~/print3d/jobs` (or `$PRINT3D_JOBS`), and
print3d reads the photos you point it at. Your printer clearances are saved in
`~/print3d/fits.json`, the printer you chose in `~/print3d/printer.json`.
- **Network:** print3d itself makes no network calls. Installing the plugin asks
to add its Python dependencies (Pillow, mcp) to Hermes's environment, and on
first start `uvx` downloads them from PyPI for the server's own environment.
The 3D view loads three.js from cdn.jsdelivr.net when you open it. A shop
listing's URL is recorded, never fetched.
- **The printer:** nothing is sent to it. You print from Studio.
- No telemetry, no credentials, no background processes beyond the MCP server
Hermes starts.
## Other agents
For Claude Code, Codex, Cursor or Gemini CLI, or to point Hermes at a print3d
you installed yourself:
```bash
uv tool install git+https://github.com/mfranzon/print3d
print3d setup
```
`setup` finds the agents on this machine, shows what it will change, and on your
yes registers the print3d MCP server with each. Claude Code and Hermes also get
the skill as a `/print3d` command, linked when supported or copied otherwise.
Rerun `setup` after upgrading to refresh a copied skill; the previous copy is
backed up beside it. Edited config files are backed up beside
themselves. `--dry-run` shows the plan without changing anything; `--agent codex`
limits it to one agent. Restart your agent afterwards.
To update, run `uv tool upgrade print3d`, then `print3d setup` again.
## Command line
Before writing a model, run `print3d doctor` (or call the MCP `doctor` tool).
It checks Blender and Bambu Studio together, reporting their paths, diagnostics
and versions when available. Windows reads Studio's executable version resource;
macOS reads its bundle's Info.plist. Neither starts Studio. Linux uses a best-effort
`--help` probe. Each subprocess probe has a five-second timeout.
The CLI exits 1 if either dependency is missing or Blender's probe fails.
Studio is ready when its executable is found; its version detection is best effort,
so a timeout, launch error or nonzero help exit does not block modelling.
Unknown versions are reported as `version: null`. Readiness is not a guarantee
that slicing will succeed. Probes use closed stdin and temporary output files
to avoid waiting on pipes inherited by helpers. On timeout the direct child is
terminated; independently spawned helpers are not guaranteed to be terminated.
`doctor` does not create jobs or change agent settings. `status` shares its
executable lookup without launching either application.
Executable jobs also check for Bambu Studio before modelling or mesh analysis.
A missing Studio installation fails the current attempt and blocks a new handoff
from an older report. Scaffolding and `--dry-run` still work without Studio;
a dry run that models geometry still needs Blender.
The same steps, without an agent:
```bash
print3d make "a 40mm nameplate that says MARCO" --script examples/nameplate.py
```
This models, checks, slices and prints a JSON report, and exits 1 if any check
fails. Without `--script`, it writes a starter `jobs/<slug>/model.py` for you to
fill in and run again.
| Command | What it does |
| --- | --- |
| `make "<prompt>"` | Model, check and slice; writes `jobs/<slug>/` |
| `view <slug>` | Rebuild `jobs/<slug>/view.html`, the part in 3D |
| `handoff <slug>` | Print sheet, renders, the `.3mf` and an STL per part, in `jobs/<slug>/handoff/` |
| `model script.py out.stl` | Run a Blender script to an STL |
| `slice model.stl` | Check and slice an existing mesh |
| `check model.stl` | Structural mesh and printability checks |
| `inspect job.gcode.3mf` | Time, filament and layers of a sliced job |
| `grid photo.jpg` | Pixel coordinates over a photo, or a zoomed `--crop` |
| `measure <slug> ...` | Record scale (or `rectify` an angled face), dimensions, outlines, unknowns and the shop `listing` in `spec.json` |
| `meet edge edge` | The corner where two edges cross, when it is hidden |
| `likeness <slug>` | Compare the mesh with the photographed outlines |
| `coupon` | Slice the fit coupon that calibrates your printer's clearances |
| `fit show` / `fit set` | The clearance per fit that scripts get as `params["fit"]`, and recording yours |
| `plan model.stl out.gcode.3mf` | Show the Studio command without running it |
| `status` | Where Blender and the printer's slicer were found, and the printer |
| `doctor` | Probe Blender and the printer's slicer before writing a model; report paths, availability and versions |
| `printer [<key>]` | Show the printer print3d slices for, or choose another (`x2d-0.4`, `p2s-0.4`, `elegoo-cc-0.4`, `elegoo-cc2-0.4`) |
| `flatten [--printer <key>]` | Rebuild a printer's presets in `src/print3d/profiles/<key>/` from its slicer's |
| `setup` | Register print3d with your agents |
| `mcp` | Run the MCP server on stdio (agents launch this) |
## Writing a model script
Plain bpy that builds geometry. `examples/nameplate.py` is the reference.
- 1 Blender unit = 1 mm.
- `params` holds the brief: `prompt`, `slug`, `text`, `intent`, `size_mm`,
`color`, `material`, the photo's `dims`, and `fit`: this printer's clearance
for a press, snug, slide or free fit.
- More than one part? Model them assembled and name each with `part()`; see
[Parts, colours and fits](#parts-colours-and-fits).
- Leave the part as mesh objects. print3d joins them, cleans the mesh, centres it
and puts it on the bed.
- Orientation is up to you. Studio's auto-orient is off, so the part prints the
way you model it.
More recipes and gotchas: `skills/print3d/references/modelling.md`.
## From a photo
Photograph the object square-on, from a distance, next to something of known
size: a bank card, a coin, an A4 sheet, a ruler. print3d turns the photo into
measurements you can trace back, and checks that the model looks like it.
```bash
print3d grid knob.jpg --crop 120,340,260,420 # read exact pixels off a zoomed crop
print3d measure knob scale front knob.jpg --ref card --points 131,352,559,352
print3d measure knob dim diameter --view front --points 610,400,790,400
print3d measure knob dim bore --mm 6 --source user
print3d measure knob outline front --points 610,300,790,300,790,520,610,520
print3d make "knob" # the model reads params["dims"]
```
Each dimension in `jobs/<slug>/spec.json` records where it came from (measured,
given by you, or assumed with a reason) and, when measured, the pixels, the
reference and a tolerance. Whatever no photo shows is listed as an unknown.
Every outlined view adds a **likeness** check to the run. The STL is projected
along that view, scaled to the photo, and laid over it. If the shape or size is
wrong, or the part is turned or mirrored, the run fails just as it does for an
overhang. `jobs/<slug>/likeness/<view>.png` shows the difference: red is in the
photo but missing from the model, blue is in the model but not in the photo.
Most photos are taken at an angle. `measure rectify` takes the four corners of a
flat face of known size (the object's own top, a card it lies on) and warps the
photo so that face is seen square-on; every later point for that view is read off
the rectified image. When a corner hides behind something, `print3d meet` finds
it where its two edges cross.
The full workflow is in `skills/print3d/references/from-photo.md`.
### Benchmark: a clothes peg from a museum photo
A wooden dolly peg from the Auckland Museum collection, photographed square-on
beside a centimetre ruler. The scale comes from the ruler (6 to 20 cm, 140 mm
across 905 px), never from the peg, and the result is scored against the
museum's catalogue record:
| | from the photo | catalogue |
| --- | --- | --- |
| length | 114.9 ± 1.2 mm | 115 mm |
| diameter, widest (across the spring) | 18.7 ± 0.7 mm | 20 mm |
| slot | 49% of the length | "approximately half way" |
The catalogue rounds to 5 mm, so both readings land inside it; the diameter's
1.3 mm gap is about what that rounding allows, not a measurement to trust to a
tenth. The knob, neck, body and slot are measured too; the catalogue has nothing
to score them against.
The peg built from those numbers (`examples/dolly_peg.py`) covers the photo's
outline at 90%, after the likeness check levels the photo by 1.5 degrees, and
slices clean: 575 layers, 49 minutes, 7.2 g. It prints standing on its knob, and
the run says so: a 115 mm part on a 14.5 mm foot is slender, so add a brim in
Studio. What the photo cannot give is recorded as such: the spring is steel wire
and is not printed, and the end chamfers are assumed.
Replay it with `pytest tests/test_peg_benchmark.py`; the end-to-end Blender and
Studio run is in `tests/test_studio_it.py`. Rebuild the media with
`scripts/workflow_media.py`.
Photo: "Peg, clothes (AM 1999.92.3-1)", Collection of Auckland Museum Tāmaki
Paenga Hira, 1999.92.3,
[CC BY 4.0](https://creativecommons.org/licenses/by/4.0/), via
[Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Peg,_clothes_(AM_1999.92.3-1).jpg).
## Instead of buying it
*A shelf bracket from its stated sizes: quote them, scale the photo from one,
measure the rest back, model, check the match, slice.
[Full-resolution video](docs/listing.mp4) · [stills](docs/listing/). Photo:
Fructibus, CC0.*
You usually don't have the thing you are about to buy, so there is no photo of it
next to a bank card. The shop listing stands in: its stated sizes are the
evidence, and one of them scales its product photos.
```bash
print3d measure hook listing https://shop.example/hook --price 4.99 --currency EUR
print3d measure hook dim length --mm 120 --source listing --quote "Dimensions: 120 x 45 x 30 mm"
print3d measure hook scale side hook-side.jpg --ref dim:length --points 52,410,1490,402
print3d measure hook dim length_measured --view side --points ... # measure a second listed size back
```
A listed dimension needs its `--quote`, the listing's own words, and carries the
listing's rounding (`--tolerance 5` for a size given in cm) into everything
measured off a photo it scaled. Measuring a second listed size back off the photo
catches a photo in perspective, a different variant, or the box's size quoted as
the product's. The run reports the listing's price beside the print's grams and
time. The workflow is in `skills/print3d/references/from-listing.md`.
### Benchmark: a shelf bracket from its stated sizes
A heavy-duty shelf bracket, photographed lying on its side, with its sizes stated
the way a listing states them: "20 x 12 cm. Width: 2 cm. Thickness: 4 mm". The
long leg scales the photo; the other three are measured back and scored against
what was stated:
| | stated | from the photo |
| --- | --- | --- |
| short leg | 12 cm (115 to 125 mm) | 126.9 ± 4.2 mm |
| width (across the strut, same bar) | 2 cm | 21.6 ± 1.2 mm |
| thickness | 4 mm | 3.4 ± 0.7 mm |
All three agree within the stated rounding plus the photo's tolerance. The short
leg is the interesting one: the listing rounds it to the centimetre, and the photo
pins it tighter, so the model uses the photo's 127 mm. A 120 mm leg would have
missed the photo by 7 mm. The screw holes (29 mm from the corner on both legs) and
the strut are measured too; the bore is assumed, since the photo sees the holes
edge-on.
`examples/shelf_bracket.py` prints it lying on its side with teardrop screw
holes, covers the photo's outline at 89%, and slices clean: 100 layers, 40
minutes, 25.6 g. The legs stand 20 mm off the table, so their sides show in
perspective; every point is read on the top plane, and 89% is about what that
allows. Steel at 4 mm carries a shelf and PLA at 4 mm will not, so the run records
it as an unknown rather than pretending the replica is a drop-in.
Replay it with `pytest tests/test_bracket_benchmark.py`; rebuild the media with
`scripts/listing_media.py`. Photo: Fructibus,
[CC0](https://commons.wikimedia.org/wiki/File:Gray_metallic_shelf_bracket_-_20_x_12_cm_-_F.jpg).
## Parts, colours and fits
Most things worth designing are more than one solid. Model every part where it
sits when assembled, name it, and say how it turns to print. The run checks each
printed object on its own, measures the gaps between parts, gives each colour its
own filament (on the X2D's two nozzles, or through the P2S's AMS), and slices all
of it into one project.
```python
c = params["fit"]["slide"] # this printer's slide clearance
plug = box(36 - 2 * c, 26 - 2 * c, 4) # sized from it, not guessed
...
part(body, "body", color="white")
part(lid, "lid", color="white", rotate=(180, 0, 0)) # prints upside down
part(name, "name", color="black", group="lid", rotate=(180, 0, 0)) # inlaid, fused with the lid
part(spare, "spare", plate=2, settings={"wall_loops": 4}) # its own plate, stronger
fit("lid", "body", "slide")
```
The run fails when parts **interfere** (they would not go together) or when a
colour part is **buried** inside its partner and would never show, and warns when
a declared fit is tighter or looser than intended. Every note names its part. In
the 3D view, each part can be hidden and the groups pulled apart.
Fits default to the usual 0.4 mm-nozzle numbers (press 0.05, snug 0.10, slide
0.20, free 0.35 mm per side). To use your printer's own, print the coupon (a pin
and eight holes from 0.00 to 0.40 mm) and record what you feel:
```bash
print3d coupon
print3d fit set --press 0.05 --snug 0.10 --slide 0.15 --free 0.30
```
From then on every script gets them in `params["fit"]` and every run measures
against them. The full guide is in `skills/print3d/references/parts-and-fits.md`.
## Hand it off
```bash
print3d handoff <slug> --currency EUR
```
`jobs/<slug>/handoff/` gets a one-page print sheet for a client, a teammate or a
print shop: renders of the part assembled and exploded, time, grams and material
cost (beside the listing's price when it replaces something you would buy), the
parts and colours, how each fit measured, every dimension with its evidence, what
is still unknown, and the open notes. The Studio `.3mf`, the 3D view and an STL
per part, in print pose, sit next to it. The sheet is one self-contained HTML
file that prints to A4.
After rerunning a job, handoff requires the latest run to complete slicing.
A failed, interrupted or dry-run attempt blocks a new handoff until another
run completes without `--dry-run`. Existing handoff files are left in place.
## What gets checked
`print3d check` and the MCP `check` tool include the same structural DFM checks
used before slicing: manifold edges, minimum volume, bed size and triangle count.
Their JSON includes `dfm`, combined `advice` and an overall `severity`. The CLI
exits 1 for errors and 0 for warnings or notes. `--project` also includes slice
analysis, as does the MCP tool's `project` argument.
- **The mesh:** overhangs steeper than 45°, bed contact, tall-and-narrow parts,
parts too thin to print. Supports are off in the pinned preset, so an overhang
is a real defect.
- **The slice:** print time, filament, and how much material each layer adds.
- **The likeness**, when you worked from a photo: outline overlap and size
against each photographed view.
- **The fits**, when there are several parts: interference, declared fits
against your printer's clearances, and colour parts that would not show.
Every problem comes with a `fix` telling the agent what to change in the script.
`jobs/<slug>/history.jsonl` keeps a record of each run.
## Develop
```bash
git clone git@github.com:mfranzon/print3d.git && cd print3d
uv venv && uv pip install -e '.[dev]'
.venv/bin/print3d setup --agent hermes # point Hermes at this checkout
.venv/bin/python -m pytest -q # unit tests
PRINT3D_STUDIO_IT=1 .venv/bin/python -m pytest -q # also runs Blender and Studio
hermes plugins validate . # check the plugin package
```
In a checkout, jobs go to `jobs/` in the repo. The repo root is the Hermes
plugin: `plugin.json`, `mcp.json` (the MCP server) and `skills/print3d` (a real
directory, so a checkout does not need symlink support). Edit the skill there;
setuptools also includes it as `print3d/skill` in installed packages.
Keep `plugin.json`'s version in step with `pyproject.toml`;
`tests/test_plugin.py` checks it.