stlbench 1.0.2

STL preparation toolkit for resin 3D printing: uniform scaling, bed packing, fill, autopack.

stlbench

STL preparation toolkit for resin 3D printing.

stlbench takes STL files and prepares them for SLA/DLP printers: automatic support-minimising orientation, uniform scaling to fit the build volume, packing parts onto rectangular print plates, filling the bed with copies, and combined scale-and-pack in one step. Support generation and hollowing are not performed -- use your slicer (Lychee, Chitubox, PrusaSlicer, etc.) after export.

Installation

pip install stlbench

Development install

git clone https://github.com/NikitaDmitryuk/stlbench.git
cd stlbench
poetry install --with dev

Quick Start

Run stlbench --help for the same command cheatsheet (copy-paste friendly).

# Full pipeline in one command: scale → orient → layout (recommended)
stlbench prepare -i ./parts -o ./plates -c configs/mars5_ultra.toml

# Or step by step:
stlbench info   -i ./parts                 -c configs/mars5_ultra.toml  # inspect
stlbench orient -i ./parts -o ./oriented   -c configs/mars5_ultra.toml  # minimise supports
stlbench scale  -i ./oriented -o ./scaled  -c configs/mars5_ultra.toml  # fit to build volume
stlbench layout -i ./scaled -o ./plates    -c configs/mars5_ultra.toml  # pack on plates

# Scale + pack all on one plate in one step
stlbench autopack -i ./parts -o ./packed -c configs/mars5_ultra.toml

# Fill the bed with copies of a single part
stlbench fill -i ./part.stl -o ./filled -c configs/mars5_ultra.toml

Or specify the printer inline without a config file:

stlbench prepare -i ./parts -o ./plates -p "153.36,77.76,165"

Commands

prepare -- Full pipeline: scale → orient → layout

stlbench prepare -i ./parts -o ./plates -c configs/mars5_ultra.toml

Runs the three preparation steps in optimal order:

1. Scale — finds the largest scale factor that fits every part inside the build volume (using an orientation-free search), then applies a uniform scale to all parts.
2. Orient — rotates each already-scaled part to minimise overhanging surface area, subject to the constraint that the part still fits the build volume in the new orientation.
3. Layout — packs the oriented parts onto the minimum number of plates, distributed as evenly as possible.

Exports one plate_NN.3mf + plate_NN.json per plate.

Key options: --overhang-angle (default 45°), --orient-candidates, --gap-mm, --post-fit-scale, --dry-run, --recursive.

info -- Analyze models (read-only)

stlbench info -i ./parts -c configs/mars5_ultra.toml

Displays a table with AABB dimensions, volume, vertex/face counts, whether each part fits the bed, maximum scale factor, and how many copies would fit (fill). No files are written.

scale -- Uniform scaling

stlbench scale -i ./parts -o ./out -c configs/mars5_ultra.toml

Computes a single scale factor so that every part fits inside the printer build volume. The largest part determines the factor; all parts share the same scale. Supports two methods: sorted (default) and conservative.

Key options: --dry-run, --no-upscale, --method, --orientation free, --post-fit-scale, --suffix, --recursive.

layout -- Pack parts onto plates

stlbench layout -i ./scaled -o ./plates -c configs/mars5_ultra.toml

Arranges already-scaled STL files onto rectangular print plates using rectpack. Exports plate_01.stl + plate_01.json with positions. Multiple plates are created if parts do not fit on one.

Key options: --dry-run, --gap-mm, --algorithm shelf|rectpack.

fill -- Maximum copies of one part

stlbench fill -i ./part.stl -o ./filled -c configs/mars5_ultra.toml

Packs as many copies of a single STL file as possible onto one plate. Useful for batch printing identical parts.

Key options: --scale (scale the part to fit before filling), --orient/--no-orient (minimise supports before filling), --overhang-angle, --dry-run, --gap-mm.

orient -- Minimise support structures

stlbench orient -i ./parts -o ./oriented -c configs/mars5_ultra.toml

For each STL file, searches for the rotation that minimises the total area of overhanging surfaces (faces whose downward angle exceeds the threshold). Uses a two-phase search: discrete evaluation of ~600+ candidate orientations derived from the model's own face normals and a uniform icosphere, followed by Nelder-Mead local refinement via scipy.optimize. The result is written as a new STL with the bottom at z = 0, ready for scale / layout.

When --config or --printer is supplied, the search is constrained to orientations that fit inside the build volume (non-fitting orientations receive a heavy penalty).

Key options: --config/-c, --printer/-p, --overhang-angle (default 45°), --candidates (default 200), --dry-run, --suffix, --recursive.

autopack -- Scale + layout on one plate

stlbench autopack -i ./parts -o ./packed -c configs/mars5_ultra.toml

Binary-searches for the maximum scale factor at which all parts fit onto a single plate simultaneously. Combines scale and layout into one step with a different goal: all parts on one plate, not each part fitting individually.

Key options: --orient/--no-orient (minimise supports before packing), --overhang-angle, --dry-run, --gap-mm, --margin, --post-fit-scale.

config init -- Create a starter TOML

stlbench config init -o my_printer.toml

Writes a commented profile with the same defaults as configs/mars5_ultra.toml. Use --stdout to print without saving, or --force to overwrite an existing file.

Configuration

Printer profiles are TOML files. See configs/mars5_ultra.toml for a complete example (ELEGOO Mars 5 Ultra), or generate one with stlbench config init.

Key sections:

Section	Purpose
[printer]	Build volume: width_mm, depth_mm, height_mm
[scaling]	bed_margin, post_fit_scale
[packing]	gap_mm between parts on the bed

Orientation (axis / free) and rotation sample count are not in TOML: use scale --orientation and scale --rotation-samples. With free, orientation matches the same printer-axis search as layout (permutation × random rotations), but scale picks the candidate that maximizes the group scale factor (layout still minimizes XY footprint for packing). Plate placement is only in layout. Default layout algorithm (rectpack vs shelf) is set via layout --algorithm.

Examples

See examples/README.md for a full walkthrough using the included Gendalf model (3 parts tracked via Git LFS).

Package Structure

Module	Purpose
stlbench.cli	Typer CLI application
stlbench.core	Scale factor, orientation, overhang analysis
stlbench.config	Pydantic schema + TOML loader
stlbench.packing	Shelf and rectpack algorithms
stlbench.export	Plate STL assembly and JSON manifest
stlbench.pipeline	Command runners (orient, scale, layout, fill, etc.)

Limitations

• Boolean operations are sensitive to non-manifold STL. For complex models use a mesh repair tool first.
• Supports and hollowing are not generated — use your slicer after export.

License

MIT