print3d

A 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 · stills · the benchmark.

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 4.2+, ElegooSlicer or Bambu Studio and uv on the same machine as Hermes. Then:

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: 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 instead, which registers the server in Hermes's config.yaml without the check.

Use it in Hermes

Ask for a part:

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.

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.

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:

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:

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.
• 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.

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, via Wikimedia Commons.

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 · stills. 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.

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.

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.

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:

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

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

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.