【Mechanical Design】🛠️ 01. Escaping GUI CAD: Thinking of Mechanical Design as Code

topics: [“mechanical design”, “cad”, “python”, “design philosophy”]

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📌 Introduction

Most mechanical design today is done using GUI-based CAD tools.
Have you ever thought:

“If I were asked to recreate this design again, it would be a pain”?

When you try to treat a design as a reusable asset,
purely GUI-driven workflows quickly reach their limits.

In this article, we introduce an alternative approach:
describing mechanical design as code rather than GUI operations.

This design philosophy is called
Full Code Mechanical Design.

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⚠️ The Limitations of GUI CAD

GUI CAD tools are extremely powerful for creating shapes.
However, they have a major weakness:
design intent and reasoning are hard to preserve.

For example:

• Why was this dimension chosen?
• Which parameters cause the shape to change?
• Can this design be reused elsewhere?

Such information is often buried inside
operation histories or feature trees.

As a result, designs tend to become
one-off artifacts, making reuse and automation difficult.

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💡 The Idea of Writing Design as Code

When people hear “design as code,” they often think:

“Are you saying we should abandon CAD?”

That is not the idea.

Code-based design does not reject CAD.
Instead, it means:

• Defining designs as parameters
• Expressing design decisions as conditional logic
• Preserving design rules as functions and structures

The focus shifts from the final shape to
the rules that generate the shape.

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🧠 What Is Full Code Mechanical Design?

In Full Code Mechanical Design:

• Drawings and GUI operations are not the primary deliverables
• The design itself is considered to be the code
• CAD is used for visualization and verification

The code explicitly captures:

• Dimensional dependencies
• Constraint conditions
• Design intent

This makes it possible to answer the question:

“Why does this shape exist in this form?”

even long after the design was created.

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🔍 GUI Operations vs. Code-Based Design

The differences between GUI CAD and code-based design can be summarized as follows:

Perspective	GUI CAD	Code-Based Design
Reproducibility	Human-dependent	High
Version control	Difficult	Easy with Git
Design intent	Hard to preserve	Explicit
Reuse	Manual	Parameter-driven

In particular, diffability is a major advantage
for design reviews and long-term maintenance.

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🎯 Who Is This Approach For?

This philosophy is not suitable for everyone.

It works especially well for people who:

• Rebuild designs repeatedly
• Generate many similar geometries
• Want to share or teach design rules
• Are comfortable with Python or coding in general

For one-off or single-shot designs,
GUI CAD may still be the faster option.

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🪜 How to Start Small

There is no need to convert everything to code at once.

Good entry points include:

• Writing dimension calculations as code
• Managing parameter tables in code
• Automating only part of the geometry generation

A hybrid approach—combining GUI CAD and code—is often the most practical.

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📝 Conclusion

Writing mechanical design as code is not just about efficiency.

It is a way to transform design from
a one-time task into
a reusable knowledge asset.

Rather than rejecting GUI CAD,
this approach complements it by addressing its limitations.

Simply having “code-based design” as an option
greatly expands your design freedom.

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📎 Additional Notes

This article focuses on organizing the concept of
mechanical design as code.

Implementation examples, concrete design code,
and license management are maintained here:

• https://samizo-aitl.github.io/full-code-mechanical-design/

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