Little utility to add Extruder information for Orcaslicer, to 3mf files created by colorscad

3mfmunge.py

# /// script
# requires-python = ">=3.14"
# dependencies = [
#     "lxml>=6.0.2",
# ]
# ///
# Little utility to add Extruder information for Orcaslicer, to 3mf files created by colorscad
import sys
import zipfile
import pathlib

from lxml import etree

MAPPINGS = {
        '[1, 1, 1, 1]':                 '1',
        '[0, 0.501961, 0.501961, 1]':   '2',
        '[0.501961, 0, 0.501961, 1]':   '3',
        '[0, 0, 0, 1]':                 '4',
        '[1, 0.843137, 0, 1]':          '5',
        }

def modxml(input):
    tree = etree.fromstring(input)

    for val, extruder in MAPPINGS.items():
        for part in tree.xpath(f'//config/object/part[metadata[@key="name" and @value="{val}"]]'):
            part.insert(0, etree.Element('metadata', key="extruder", value=extruder))

    return etree.tostring(tree, pretty_print=True, encoding='unicode')

def modify(srcfile, dstfile):
    with zipfile.ZipFile(srcfile) as inzip, zipfile.ZipFile(dstfile, 'w') as outzip:
        # Iterate the input files
        for inzipinfo in inzip.infolist():
            # Read input file
            with inzip.open(inzipinfo) as infile:
                if inzipinfo.filename == 'Metadata/model_settings.config':
                    outzip.writestr(inzipinfo.filename, modxml(infile.read()))
                else:
                    outzip.writestr(inzipinfo.filename, infile.read())

def usage():
        print(f'Usage:')
        print(f'  uv run {sys.argv[0]} input.3mf output.3mf')
        sys.exit(1)

def main():
    args = sys.argv[1:]

    # Usage
    if len(args) != 2:
        usage()

    input_path = pathlib.Path(args[0])

    # First argument (input file) must exist
    if not input_path.is_file():
        print(f'Error: Input file not found: {input_path}', file=sys.stderr)
        sys.exit(1)

    output_path = None

    # Output must not exist
    output_path = pathlib.Path(args[1])
    if output_path.exists():
        print(f'Error: Output file already exists: {output_path}', file=sys.stderr)
        print('Overriding this is a future feature.')
        sys.exit(1)

    return modify(input_path, output_path)

if __name__ == '__main__':
    main()

snippets shamelessly stolen from https://techoverflow.net/2020/11/11/how-to-modify-file-inside-a-zip-file-using-python/