printfins.com from a terminal: fin one part or a whole folder, then open the results in any slicer. It's the answer for Bambu Studio, which has no plugin API: run the parts through this, open the 3MFs in Bambu.

Same engine as the site and every plugin (plugins/shared/engine/computeFins), and the same settings: the flags are generated from plugins/shared/engine/options.json.

support-fins part.stl                          # -> part-fins.3mf next to it (part + fins)
support-fins part.stl --rot 0,35,0             # pose it first: the site's X · Y · Z readout
support-fins *.stl --gap 0.3 --coverage 70        # PETG: a wider Support gap
support-fins part.stl -o out.stl               # one STL with part + fins merged
support-fins part.stl --fins-only              # part-fins-only.stl, lines up with part.stl
support-fins plate.3mf --object 2              # a 3MF with several objects: pick one
support-fins part.stl --json                   # one JSON line per file (stats + summary)
support-fins --help                            # every setting, with the site's defaults

Rotation. The part is finned the way it sits in the file (z up), unless --rot turns it. --rot takes the numbers printfins.com shows under the part ("X 35° · Y 0° · Z 0°" is --rot 35,0,0), in the same order (three.js Euler XYZ), so a pose found on the site carries over. The output is posed, centred over the origin, and seated on z = 0, as the site exports it. --fins-only instead lines the fins up with the part as it is in your file, so it can't take --rot.

A Support Fins 3MF (the site's or this tool's) is refused as input: it already has fins. Settings the site would hide (--sway-reach without --sway) run but warn.

Settings are the site's, in the site's units: percent sliders take 0-100 (--coverage 70, --tine-density 50), on/off settings are --sway / --no-tines.

What it tells you. One line per file: walls, tines, and anything left unsupported (overhangs too shallow for a fin this way up, pieces that start in mid-air). That is a report, not a failure: exit 0. Exit 1 = a file couldn't be read or finned (the other files still are); exit 2 = bad arguments, nothing ran.

Running it

The download (printfins.com ▸ Plugins, or support-fins.mjs on the plugins-latest release) is the whole tool in one file:

deno run -RW support-fins.mjs part.stl                 # Deno 2
node support-fins.mjs part.stl                         # Node 20.10+

From a checkout (python3 plugins/cli/build.py makes that file):

deno run -RW plugins/cli/support-fins.js part.stl      # Deno 2
node plugins/cli/support-fins.js part.stl              # Node 20.10+

Single-file binary (no Deno or Node needed to run it, ~70 MB):

deno compile -RW --include plugins/shared/engine/options.json \
  -o support-fins plugins/cli/support-fins.js

For an AI client (Claude Code, Claude Desktop), the same tool is an MCP server: plugins/mcp/.

Code

support-fins.js — the entry: gives cli.js a file system (Deno or Node) and an exit code.
cli.js — flags, pose, read STL/3MF, computeFins, write. No file system of its own.
tests/cli.test.js — deno test -A plugins/cli/tests/. Runs in memory: CLI fins equal computeFins on the posed part, and match the website's own path on lbracket@35.
The summary line is plugins/shared/engine/report.js, word for word with the Python hosts' host_report.