Buoyant Prints Infill Solver

infill-solver.py solves for Bambu Studio Sparse infill density (%) by re-slicing a configured .3mf and reading predicted mass from G-code metadata.

Use it for neutral/positive/negative buoyancy targets, with optional extra mass and extra displaced volume (for example, line on a finger spool).

How It Works

• Reads model volume directly from the 3MF mesh (same geometry the slicer uses).
• Computes target mass: water_density * (volume + extra_volume) - extra_mass and applies optional buoyancy bias.
• Binary-searches infill density by calling the Bambu Studio CLI and parsing: ; total filament weight [g] : <value>
• Uses a practical 0.1% infill search resolution.
• Writes the final infill back into the original .3mf (optional backup flag available).

Requirements

• Python dependencies: stdlib only (no requirements.txt needed).
• Docker compose service bambustudio is configured and runs successfully.
• Wrapper script exists: run-infill-solver.sh.
• Input .3mf already has print settings finalized except sparse infill density.

Minimal Docker Service

Your docker-compose.yml needs a bambustudio service that can run:

• Bambu Studio CLI binary (default used by wrapper: /opt/bambustudio/bin/bambu-studio)
• Python 3
• Volume mount for this project directory at /data

Quick Start

Run from the host with the wrapper (executes inside the container):

"/media/internal/Development/3D-printing/Buoyant Prints/run-infill-solver.sh" \
  "/media/internal/Development/3D-printing/Buoyant Prints/Finger-Spool.3mf" \
  --water-density 1.0 --buoyancy neutral

Note: --water-density 1.0 overrides the script default (1.025 for salt water).

Extra mass/volume (line on a spool)

"/media/internal/Development/3D-printing/Buoyant Prints/run-infill-solver.sh" \
  "/media/internal/Development/3D-printing/Buoyant Prints/Finger-Spool.3mf" \
  --water-density 1.0 \
  --extra-mass-g 12.4 \
  --extra-volume-cc 9.2

Key Flags

• --volume-cc: override auto-read 3MF volume
• --extra-volume-cc: additional displaced volume (cm^3)
• --extra-mass-g: additional carried mass (g)
• --water-density: 1.000 for fresh, ~1.025 for salt
• --tolerance-g: stop when abs(error) <= tolerance (default 0.02 g)
• --buoyancy: neutral, positive, or negative
• --bias-g: bias applied for positive/negative buoyancy (default 0.05 g)
• --backup: writes <model>.3mf.bak before updating the source file
• --verbose: show Bambu CLI output each iteration
• --dry-run: print computed target mass and exit (no slicing, no file write)

Example Output

volume from 3MF: 19.0621 cm^3
target mass: 19.0621 g
iter 01: infill= 50.00%  predicted_mass=   20.60 g  target=   19.06 g  err=  +1.54 g
iter 02: infill= 25.00%  predicted_mass=   19.35 g  target=   19.06 g  err=  +0.29 g
iter 03: infill= 12.50%  predicted_mass=   18.72 g  target=   19.06 g  err=  -0.34 g
iter 04: infill= 18.80%  predicted_mass=   19.05 g  target=   19.06 g  err=  -0.01 g

Operational Notes

• The script updates the source .3mf in place.
• Use --backup when you want an on-disk rollback point.
• Close the same project in Bambu Studio while the solver runs to avoid stale UI state.

Known Limitations

• Uses slicer-predicted mass, not measured print mass; calibration/flow error can shift real results.
• Assumes monotonic mass vs infill; unusual presets may reduce search quality.
• 3MF volume extraction is mesh-based and may differ slightly from CAD solid volume.
• Does not model flooding, trapped-air leaks, deformation, or material water absorption.
• Multi-plate or process-specific overrides in some projects may still require manual verification in GUI.