Weekend Rec Builds: 3D Print Estimator

Source: Dev.to

Introduction

This project began with a simple question from my brother:

“How much filament will this use, and how long will it take?”

He had about 100 individual STL files to check. While a slicer can give estimates, opening, slicing, and reading the stats for each file quickly becomes tedious.

What the 3D Print Estimator Does

A stand‑alone, slicer‑agnostic utility that scans STL files directly and provides reasonably accurate numbers for:

• Filament length
• Filament mass
• Print time

It works from the command line or via a lightweight web interface.
GitHub repository – 3D‑Print‑Estimator

How It Works

Geometry Analysis

The estimator reads both binary and ASCII STL files and walks every triangle in the mesh, updating:

• Volume (via signed tetrahedral volume)
• Surface area
• Bounding‑box dimensions

Key functions in estimator.py:

# estimator.py
def read_stl(...):
    # parses STL file
    ...

def accumulate_triangle_stats(...):
    # updates bounds, area, volume
    ...

Material & Time Estimation

Once geometry is known, the estimate() function converts it into printable material and time estimates.

Shell Calculation

shell_thickness = settings.perimeter_count * settings.nozzle_diameter_mm
shell_volume = stats.surface_area_mm2 * shell_thickness

Infill Calculation

internal_volume = max(stats.volume_mm3 - shell_volume, 0.0)
infill_volume = internal_volume * settings.infill_density

Filament Length & Mass

import math

filament_cross_section = math.pi * (settings.filament_diameter_mm / 2) ** 2
filament_length = total_extrusion_volume / filament_cross_section
filament_mass = (total_extrusion_volume / 1000) * settings.filament_density_g_cm3

Print Speeds

Three speeds are used:

• perimeter_speed_mm_s
• infill_speed_mm_s
• travel_speed_mm_s

The tool provides approximations, not G‑code‑level precision, but the heuristics work surprisingly well.

Usage

Command‑Line Interface

python estimator.py --config printer-config.json

• Scans all .stl files in the current folder.
• Outputs CSV by default (options: JSON, XLSX).
• XLSX mode adds formulas for totals and hour/minute formatting (build_workbook()).

Web Interface

python estimator.py --serve --port 5000

• Open.
• Upload a single STL or a ZIP of STLs.
• Receive a clean table of results with one‑click download links (CSV, JSON, XLSX) generated as data URIs.

The web UI is self‑contained, using a Flask‑rendered HTML string defined in WEB_TEMPLATE.

Configuration

All printer‑specific settings live in printer-config.json. Example:

{
  "layer_height_mm": 0.2,
  "nozzle_diameter_mm": 0.4,
  "perimeter_count": 2,
  "top_layers": 4,
  "bottom_layers": 4,
  "infill_density": 0.25,
  "perimeter_speed_mm_s": 40.0,
  "infill_speed_mm_s": 60.0,
  "travel_speed_mm_s": 120.0,
  "filament_diameter_mm": 1.75,
  "filament_density_g_cm3": 1.24,
  "travel_factor": 0.1
}

Adjust these values to match your printer, material, or desired printing preferences; the estimator updates automatically.

What It Is Not

• A replacement for your slicer
• A minute‑by‑minute print‑time predictor
• A handler for variable layer heights, retractions, coasting, acceleration, or machine‑specific quirks

Primary Benefits

• Quickly answer “Do I have enough filament?”
• Get a ballpark estimate of print duration
• Identify which STLs are weekend‑size projects versus quick prints

Future Improvements

• Per‑model configuration overrides
• Optional real‑world calibration (feed a known model + actual print time to adjust heuristics)
• A more polished web UI
• Batch mode to compare the cost of different print settings

This project remains small enough to stay enjoyable while offering plenty of room for experimentation and growth.