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# Painting, but with light
- URL: https://www.notation.design/archive/painting-with-light/
- Published: 2026-09-10T06:23:00.000Z
- Updated: 2026-10-10T06:33:25.000Z
- Description: Why tiny changes in CAD surface curvature can dramatically change reflections, and therefore how refined, precise or premium a product feels.
- Author: Iwan Hänggi
- Tags: Thinking, CAD Development

I am working on an automotive project at the moment, and it made me think about the way I approach CAD work.

I remember a few eye-rolls over the years when I started obsessing over tiny details and talking about Class-A surfaces, curvature, smoothness, G2 or G3 continuity.

This is the jargon designers use when we are trying to create a very refined CAD model.

But I am not simply trying to find a 3D shape that ticks all the requirement boxes or wraps nicely around everything inside.

I am trying to control the impression someone has when they look at the product — and how it makes them feel about the product and the brand.

In that sense, surfacing is a bit like **painting the product with light**.

How can I shape and control a surface so that light and shadow create the right impression?

A tiny change in curvature may barely affect the physical dimensions of the product, but it can significantly change its reflections — and therefore how refined, precise or premium it feels.

Fractions of a millimetre can make a surprisingly large visual difference.

That is why I sometimes obsess over 0.1 mm when I design a product.

I posted this on LinkedIn originally: [https://lnkd.in/p/e3YRMUTB](https://lnkd.in/p/e3YRMUTB?ref=notation.design)

Related: [Cad Development](https://www.notation.design/archive/category/cad-development/)