STL to SVG conversion script using OpenSCAD. Takes an STL and projects it to the defined plane (default: XY), then saves the result as SVG.

stl_to_svg.scad

FileToLoad = "";
Plane=0; // 0: XY, 1: XZ, 2: YZ

echo("File:", FileToLoad);
projection() {
    if (Plane == 0) {
        echo("Plane: XY");
        import(FileToLoad);
    } else if (Plane == 1) {
        echo("Plane: XZ");
        rotate([90, 0, 0]) import(FileToLoad);
    } else if (Plane == 2) {
        echo("Plane: YZ");
        rotate([0, 90, 0]) import(FileToLoad);
    }
}

stl_to_svg.sh

#!/bin/bash

### Usage ###
# stl_to_svg.sh [-p {xy|xz|yz}] input.stl [output.svg]
#
#   -p = Projection plane, xy, xz or yz
#   input.stl = Input file
#   output.svg = Output file, if not provided will default to input.stl.svg
#

#set -xe

OPENSCAD="/path/to/openscad"
SCAD="/path/to/stl_to_svg.scad"

plane=0
while getopts "p:" opt; do
    case $opt in
        p)
            case $OPTARG in
                xy)
                    plane=0
                    ;;
                xz)
                    plane=1
                    ;;
                yz)
                    plane=2
                    ;;
                *)
                    echo "Invalid plane definition, accepted values are xy, xz and yz"
                    exit -1
                    ;;
            esac
            ;;
    esac
done

shift $((OPTIND-1))

[ "${1:-}" = "--" ] && shift

STL="$1"
SVG="$2"
[ -n "$SVG" ] || SVG="$STL.svg"

"$OPENSCAD" -o "$SVG" -D FileToLoad="\"$STL\"" -D Plane=$plane "$SCAD"

Nice and useful, thanks a lot. Since Prusaslicer now allows to modify models with SVGs this comes quite handy!