Extract thumbnail from 3mf via Bambu Lab printer FTPS

README.md

Intro

Downloads a 3MF file from a Bambu Lab printer via it's FTPS service when the printer is in LAN mode. The embedded thumbnail is then extracted from the 3MF file.

This script makes little-to-no effort to validate files exist or are in the correct format and is provided as-is. I take no responsibility for any loss of data or damages caused. Use at your own risk.

Usage

Run the script with arguments <host> <access_code> <model name>. Example:

python3 bblab_fetch_image.py 192.168.1.123 12345678 "My super model.3mf"

By default models are downloaded to ./models, and images to ./images

bblab_fetch_image.py

import os
import ssl
import sys
import ftplib
import zipfile
import xml.etree.ElementTree as ET

class ImplicitFTP_TLS(ftplib.FTP_TLS):
    """
    FTP_TLS subclass that automatically wraps sockets in SSL to support implicit FTPS.
    see https://stackoverflow.com/a/36049814
    """
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._sock = None

    @property
    def sock(self):
        """Return the socket."""
        return self._sock

    @sock.setter
    def sock(self, value):
        """When modifying the socket, ensure that it is ssl wrapped."""
        if value is not None and not isinstance(value, ssl.SSLSocket):
            value = self.context.wrap_socket(value)
        self._sock = value

def download_model(host, access_code, model, download_path='.'):
    download_path = os.path.abspath(download_path)
    os.makedirs(download_path, exist_ok=True)

    ftp = ImplicitFTP_TLS()
    ftp.connect(host=host, port=990, timeout=10)
    ftp.login(user='bblp', passwd=access_code)
    ftp.prot_p()
    # Sometimes the 3mf is present in the FTP root, other times it's in
    # "cache", try both.
    with open(f'{download_path}/{model}', 'wb') as fp:
        try:
            ftp.retrbinary(f'RETR {model}', fp.write)
        except:
            ftp.cwd('cache')
            ftp.retrbinary(f'RETR {model}', fp.write)
    ftp.quit()

def extract_image(model_path, extract_path="."):
    """
    Extracts a single file from a 3MF (ZIP) archive.
    """
    if not zipfile.is_zipfile(model_path):
        print(f"Error: {model_path} is not a valid 3MF file.")
        return

    try:
        with zipfile.ZipFile(model_path, 'r') as archive:
            # Attempt to fetch the name of the plate being printed
            # from one of two relationships files
            plate = None
            if '_rels/.rels' in archive.namelist():
                plate = get_plate(archive.read('_rels/.rels'))
            elif plate is None and 'Metadata/_rels/model_settings.config.rels' in archive.namelist():
                plate = get_plate(archive.read('Metadata/_rels/model_settings.config.rels'), 'http://schemas.bambulab.com/package/2021/gcode')
            else:
                plate = 'Metadata/plate_1'

            image_path = f'{plate}.png'

            if image_path in archive.namelist():
                extract_name = f'{os.path.splitext(os.path.basename(model_path))[0]}.png'
                extract_path = os.path.abspath(extract_path)
                image = archive.getinfo(image_path)
                image.filename = extract_name
                archive.extract(image, extract_path)
                print(f"Extracted {image_path} to {extract_path}/{extract_name}")
            else:
                print(f"Error: {image_path} not found in the 3MF archive.")
    except Exception as e:
        print(f"An error occurred: {e}")

def get_plate(rels, type='http://schemas.openxmlformats.org/package/2006/relationships/metadata/thumbnail'):
    try:
        root = ET.fromstring(rels)
        for child in root:
            if (child.attrib.get('Type') == type):
                return os.path.splitext(child.attrib.get('Target'))[0].removeprefix('/')
    except Exception as e:
        return None

if __name__ == "__main__":
    if len(sys.argv) < 4:
        print("Host, access code and model name required")
    else:
        printer_ip = sys.argv[1]
        access_code = sys.argv[2]
        model_name = sys.argv[3]

        download_path = 'models'
        image_path = 'images'

        download_model(host=printer_ip, access_code=access_code, model=model_name, download_path=download_path)
        extract_image(f'{download_path}/{model_name}', extract_path=image_path)