preFlight

The Engineer's Slicer

preFlight is an advanced 3D printing slicer built for precision and performance. Building on the Slic3r legacy as a spiritual successor to PrusaSlicer, it offers exclusive features and a comprehensive under-the-hood overhaul, bringing the entire dependency stack up to modern standards. Given this massive modernization, preFlight has evolved beyond the constraints of the original codebase, making upstream merging irrelevant.

oozeBot

Based in Georgia, USA, oozeBot is a small but ambitious team currently preparing for the take-off of our Elevate line of 3D printers. preFlight is the cornerstone of the ecosystem we are building - a genuinely new option in the 3D printing space designed to benefit all makers, regardless of the hardware they use.

Discover preFlight

Want to see what makes preFlight special? Head over to our Feature Showcase to view screenshots, learn more about unique features, and join the discussion.

Donate

While preFlight is open-source and free for everyone, your support helps us maintain the infrastructure, fund R&D, and keep our team in orbit. If you find value in our tools, consider contributing to the mission.

Support the preFlight Mission (via Stripe)

Requirements

Windows, Linux, macOS, and Raspberry Pi.

Windows: Download the portable zip from GitHub Releases and extract. Requires the Microsoft Visual C++ Redistributable (x64) - install this first if preFlight won't launch.

macOS: Download the DMG from GitHub Releases. Requires macOS 11.0+ (Big Sur or later), Apple Silicon only. All builds are signed and notarized by Apple.

Linux: Download the AppImage from GitHub Releases, make it executable (chmod +x), and run. No installation required.

Raspberry Pi: RPi 5 running 64-bit Raspberry Pi OS (Bookworm or Trixie). Download the aarch64 .deb package from GitHub Releases.

Security & Authenticity

To ensure the integrity of your installation and protect yourself, please follow these security guidelines:

Official Downloads: Only download preFlight binaries directly from our GitHub Releases page. We do not distribute preFlight through third-party mirror sites.
Verified Signature: All official Windows binaries are digitally signed by oozeBot, LLC using an Organization Validation (OV) Code Signing Certificate.
Verification: Before running the installer, right-click the file, select Properties, and navigate to the Digital Signatures tab. Ensure the "Name of signer" is explicitly listed as oozeBot, LLC.
Safety First: If you receive a "Windows protected your PC" (SmartScreen) warning on a file that is not signed by oozeBot, LLC, do not proceed with the installation and report the issue immediately.
macOS Notarization: All official macOS DMGs are signed with an Apple Developer ID certificate and notarized by Apple. macOS will verify the signature and notarization automatically on first launch. If Gatekeeper warns that the app is from an unidentified developer, the DMG is not an official release.

Why preFlight?

| What You Get | The Difference | |--------------|----------------| | Athena Perimeter Generator | Independent overlap control no other slicer offers | | Interlocking Perimeters | Enhanced Z-bonding without added cost or complexity | | True 64-bit Architecture | No coordinate overflow, no silent failures | | High Precision | Clipper2 compiled with 10-decimal high precision | | In-Memory Processing | No temp files, ~50% less RAM usage | | Modern Stack | C++20, Clipper2, Boost 1.90, CGAL 6.1, OpenCASCADE 7.9, Eigen 5.0 |

Flagship Features

Athena Perimeter Generator

In Greek mythology, Athena defeated Arachne not through greater complexity, but through discipline and precision. We named our perimeter generator after her for the same reason.

Why Athena Exists

We forked Arachne to modernize it in several ways. Athena uses fixed extrusion width instead of variable and independent overlap control between perimeters. Arachne calculates overlap automatically. Athena lets you specify exactly how much perimeters overlap. It even enables negative overlap for creating gaps between perimeters.

Unique Controls

| Setting | What It Controls | Range | |---------|------------------|-------| | Ext. perimeter/perimeter overlap | Gap between external wall and first internal wall | -100% to +100% | | Perimeter/perimeter overlap | Gap between all internal perimeters | -100% to +80% | | Perimeter compression | How aggressively perimeters narrow in tight areas | |

Positive overlap: Perimeters merge into each other (stronger bonding)
Zero overlap: Perimeters just touch
Negative overlap: Gap between perimeters (useful for flexible or soft materials)

Additional Characteristics

Fixed extrusion widths with variation absorbed in spacing, not width
Predictable wall shell thickness
Full thin wall support

When to Use Athena: You need control over how perimeters bond, want consistent external perimeter width, or are tuning for strength/flex behavior.

When to Use Arachne: You prefer automatic overlap calculation or don't care about perimeter spacing.

Interlocking Perimeters

A novel approach to layer bonding using spacing variation and compression bonding - fundamentally different from "brick layers".

How it works:

Uses Athena's skeletal trapezoidation engine to generate interlocking shells - naturally handles narrow channels and bead count transitions
Three bead width tiers that alternate between layers, keeping inter-shell gaps uniform
Geometric centerline spacing for overlap bonding - no over-extrusion at shell boundaries
All beads printed at constant layer height (no Z-axis manipulation)

Key distinction from "brick layers": | Aspect | Brick Layers (others) | Interlocking (preFlight) | |--------|----------------------|--------------------------| | Mechanism | Height variation (Z-axis) | Spacing variation (X/Y axis) | | Bead heights | Variable (half/full) | Constant | | Bonding type | Geometric interlocking | Compression bonding |

Benefits:

5-15% strength increase (estimated)
No material or time penalty at 100% strength
Maintains dimensional accuracy (constant layer heights)

Exclusive Features

True 64-bit Architecture

64-bit coordinate types throughout.

// PrusaSlicer/OrcaSlicer/SuperSlicer:
using coord_t = int32_t;  // Overflow risk

// preFlight:
using coord_t = int64_t;  // No overflow, native Clipper2

Why it matters:

32-bit coords overflow in cross products with large coordinates
Clipper2 uses 64-bit internally - type mismatch causes bugs
Large print volumes can exceed 32-bit range

In-Memory G-code Processing

Zero temp files during slicing:

No disk I/O during slicing
~50% less RAM (no per-line string overhead)
Faster slicing (no file system operations)

Multi-Type Support Painting

Mixed support types on a single object.

Paint Snug (Blue) - Strong, close contact
Paint Grid (Orange) - Balanced strength/removal
Paint Organic (Green) - Easy removal, delicate areas

Strong supports under critical overhangs, easy-to-remove supports elsewhere. All on one print.

Seam System

A comprehensive seam management system for hiding layer start/stop points.

Nip and Tuck Seams:

Seam shaping modes that push the external perimeter inward at the seam point, creating a V-shaped channel that absorbs start/stop blobs. The first inner perimeter is automatically trimmed to accommodate the disturbance.

| Mode | Behavior | |------|----------| | Nip/Tuck | Both start and end pushed inward - full V-notch | | Nip | Only start pushed inward - conceals the start point | | Tuck | Only end pushed inward - conceals the end point | | Alt. Nip/Tuck | Alternates Nip and Tuck per layer - distributes disturbance across both sides |

Configurable notch width (1-3x extrusion width) and corner threshold angle. Automatically skipped at sharp corners where the geometry already hides the seam.

Painted Seam Alignment:

Bidirectional blending system for stable vertical and diagonal seam tracking on painted enforcer regions. Forward pass tracks diagonal seams while filtering vertex noise, backward pass straightens early-layer convergence lag.

**Paint-on Seams Line Drawin

PreFlight

Install / Use

README