As you saw in example 4.6 in the book, unfolding a developable surface in SketchUp is very easy using the Unfold plugin. What do you do then, if you have a doubly-curved shape, such as the one shown above (from chapter 6)? Obviously, you can’t just “flatten” it without distorting it (take the Mercator projection of world maps for an example of how unwrapping a sphere can lead to significant distortions). In this case, it might be a good strategy to unfold the surface in strips using the same technique described in example 4.6. This gives you the ability to cut the surface into separate parts that can then be assembled using gluing, welding etc. The image below illustrates how this looks after flattening.

This can now be done much easier with my Unwrap and Flatten Faces extension.

As you may have noticed, I also added some glue tabs using the Glue Tabs plugin (see chapter 4 for details). In order to make this work, you may need to turn on hidden geometry display (in the View menu).

After printing, you can cut the shape out…

… and assemble it. My model here is a bit rough because I only used thin paper and discontinuous glue spots. But you get the idea.

Happy modeling!

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