Distinctions

What Makes omdl Distinct from Other OpenSCAD Libraries

The OpenSCAD Mechanical Design Library (omdl) began as the work of an electrical engineer without formal training in mechanical engineering or graphical design. Its approach reflects patterns drawn from electrical hardware description languages, which may feel unconventional to designers accustomed to geometry-first or graphics-driven workflows.

It is intentionally positioned differently from widely used OpenSCAD libraries such as MCAD and BOSL2. While all three support parametric modeling, they target different abstraction levels and workflows.

1. Mechanical-Engineering-First Abstraction

omdl is designed around mechanical design intent, not just geometry creation.

• Parameters represent physical concepts (lengths, angles, tolerances, fits)
• Modules reflect mechanical parts and operations, not just shapes
• Design choices emphasize manufacturability and assembly

In contrast:

• MCAD focuses on providing a catalog of reusable mechanical parts
• BOSL2 focuses on robust geometric primitives and utilities

omdl treats geometry as a consequence of mechanical decisions, not the starting point.

2. Emphasis on Structured Parameters

omdl encourages the use of structured, self-describing parameters rather than long positional argument lists.

omdl takes the view that design application flexibility is increased by providing detailed construction options through careful parameterization and by managing those parameters as configurations with defaults, inheritance, and instance-level control. Designers should be able to create useful mechanical parts using defaults, while still retaining the ability to drill down into low-level geometric details when required.

This results in:

• More readable designs
• Fewer silent failures
• Easier long-term maintenance

By comparison:

• MCAD often relies on positional parameters
• BOSL2 provides powerful helpers but leaves structure decisions to the user

3. Unit-Aware Design Philosophy

omdl natively supports unit-aware modeling, making mixed-unit mechanical work safer and clearer.

Key ideas:

• Explicit unit conversion (length(), angle())
• Reduced risk of inch/mm confusion
• Clear documentation of expected units

Most other libraries:

• Assume a single unit system (usually millimeters)
• Leave unit discipline entirely to user convention

For mechanical engineers working from drawings or standards, this is a major differentiator.

4. Workflow-Oriented Organization

omdl mirrors how mechanical designs evolve. This is reflected directly in the library structure:

• Types
• Common
• Units
• Data
• Math
• Shapes
• Transforms
• Tools
• Models
• Parts

Other libraries are typically organized by shape type, not design process.

5. Documentation as a First-Class Feature

omdl is written to be self-documenting by design:

• Doxygen-style comments embedded in source
• Generated API documentation in multiple output formats (HTML, PDF, etc.)
• Parameters explained in engineering terms

The goal is that reading the documentation teaches mechanical design usage, not just syntax.

By contrast:

• MCAD documentation is sparse and example-driven
• BOSL2 documentation is extensive but geometry-centric

6. Conservative, Predictable Behavior

omdl favors:

• Explicit behavior over “magic”
• Predictable defaults
• Minimal global state

This makes designs:

• Easier to audit
• Easier to debug
• More suitable for long-lived or shared projects

Differentiation Summary

Feature	omdl	MCAD	BOSL2
Primary Focus	Mechanical design intent	Part catalog	Geometric power tools
Units	Explicit, unit-aware	Implicit	Implicit
Parameter Style	Structured & named	Positional	Mixed
Workflow Orientation	Yes	No	No
Documentation Depth	High, engineering-centric	Minimal	High, geometry-centric
Target User	Mechanical engineers	Hobbyists & general users	Power users

omdl is not just a geometry library, it is a mechanical design framework for OpenSCAD, built to reflect how engineers think, document, and maintain real mechanical systems.