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Flattening/ unfolding a low poly model in sketchup

Posted: April 09, 2010
Hey everyone

I've been toying with Google Sketchup for a while now. I've made a low poly model of a mask. I intend to build this mask for real with stainless steel sheet. Problem is, I don't know how to flatten the mask in either one or a couple of flat pattern projections.

My original intent was to label each poly, copy it to a different sheet and align in 2d so I could print, cut and use as a template for the real life component. This I did but I end up with to many, to small components; it will be almost impossible to get this in steel.

I've found one plugin for sketchup that will allow me to flatten but ofcourse you have to fork over 10 bucks to do so.

In conclusion: is there a plugin or a different program that will easily generate one or multiple flat patterns for my 3d model? maybe using a different 3d prog?

Posted: April 15, 2010
Well there is the Waybe plugin at: http://waybe.weebly.com/ but it doesn't cost $10 it costs much more than that (it starts at $50 and goes all the way to $200 for the full commercial version) but there is a simpler free plugin that can do unfolding in Sketchup called Unfold by Jim Foltz.

This is the address:


This is the location of the Sketchup Plugins Blog. Download it from that page and follow the instructions for installation. This plugin is not as easy to use as Waybe but it is easier than to unfold and align a flattened pattern by hand.

Your other choice is to export the 3D model to Colada file format and import it into the free open source program Blender 3D (you can download it in the Blender web site at: http://www.blender.org/ and you can import it with the Colada 1.4 filter (not the Colada 1.3 filter) and then unfold it in the free open source program Blender with the free Unfold script or the free B-Paperizer script.

The Blender Unfold script already comes installed with Blender but the B-Paperizer has to be installed separately. In order to use any of those two scripts you have to install full Python cause they do not work with the simpler Python that Blender already includes. Full Python is available for free in the Python web site: http://www.python.org/ and it has an automatic installer.

If you do use the second alternative (I don't know if you have any experience in Blender) you have to install the Python that corresponds to your version of Blender and you can tell that in the Blender download page. The latest production ready version of Blender is 2.49b and for that version you have to use Python 2.6.5 Windows installer (an automatic installer) if you have Windows, if you have a Mac you don't need to install full Python cause OS X already comes with a full Python already pre-installed.

Do not use 64 bit Blender, install 32 bit Blender (32 bit Blender has an automatic Windows installer) and the same for Python (32 bit Python) cause they are more compatible with the unfolding scripts.

I recently wrote a free e-book that tells you a lot about paper unfolding in 3D programs but is based mainly in Blender and it can teach you a lot about unfolding. I just put a post in this forum about it in the CG News and Events section, more exactly here: http://www.3dmd.net/forum/3d-discussion-6384.html . The book also tells how to install the B-Paperizer script and also how to use both scripts. There is also a reference in the book on page 22 about a quicker tutorial on how to use the Blender Unfold script. The book comes in a zip file that also includes the latest version of the free B-Paperizer script.

You can also download the B-Paperizer script for Blender here:


In that page click on the Programming link at the top and in the menu to the left that appear click on the last item B_paperizer and then in that page right mouse click on the white colored words here and select Save Link As and save the script on a temporary folder so you can place it in the Blender scripts directory later on.

The book has explanations that can help you understand better the problem that you are having about too many small pieces, it doesn't always have to be like that because there are tricks to go the other way and that is to increase the number of polygons, divide it into sections and smooth the lines later and that can produce a cleaner pattern but you have to read the book in order to understand this concept fully so that is up to you.

Remember that none of these free unfolders can compensate for material thickness cause they were designed for paper modeling mostly in which you have to compensate for cardboard thickness (which is a relatively thin material) manually but rarely. Despite this as you seem to know already the principles for sheet metal unfolding and paper unfolding are very, very similar in many cases so some people do use those free unfolders for such a purpose and also for other purposes such as fabric patterns.

For the ability to compensate for material thickness you will need a commercial plugin with a commercial program but this can go all the way to thousands of dollars.

Now that doesn't mean that you cannot do small manual adjustments (trimming a bit of some edges) by hand and a lot of times you don't need to do it anyway but that will depend on what you are unfolding and how thick the material is. The bottom line is that it can be done.

I hope that this helps. Smile
Posted: May 14, 2010
Oh crap I completely forgot about this post...sorry man. I realy appreciate the (very extensive) help and will defenitely look into it.

In the meantime I've unfolded the model manualy (shoot me) and am working on the mask.
Posted: May 15, 2010
If you plan to do any more sheet metal unfolding in the future it would be a good idea if you read the book, I think that it could teach you a few things about unfolding and many, many of the concepts can be translated into sheet metal unfolding/welding easily.

Trust me if you read it and practice with it, even if you practice by creating a few simple paper model you will get a much better grasp of the subject even for your type of work, I feel strongly in that direction. Smile
Posted: May 18, 2010
I've been trying the unfold plugin and it works a treat! I can even make angled, mitered joint cone layouts for sheet steel now, pretty sweet!
Posted: September 29, 2011
It really is very flexible. There is a helluva lot that can be done in sheet metal unfolding with these same scripts.

The one thing to be careful with is that metal is usually very thick in comparison to cardboard and sometimes one has to compensate much more for metal thickness but with a little practice this can be overcome and it still allows one to do a lot of things.

The other difference with cardboard is that cardboard does allow a slight amount of folding in the other direction of a compound curve while with metal this is not possible unless the base metal pattern is beaten into another shape by somebody with such skills.

The other script for unfolding, B-Paperizer by Czestmyr is in my opinion even better. As you found out there are more uses for them than just paper models, another one of them is the creation of patterns for the creation of clothing and in that case it is the opposite of metal in the fact that fabric allows much more flexibility in the second direction of a compound curve (much more than cardboard or paper too of course) even though it stills have a limitation.

It is just wonderful to see how many things can be created with the proper use of these tools, at first many people don't know how far it can go but it does goes very far.

And even if a 3D modeling program does not have as much precision as a CAD program has in many instances and for many applications it has more than enough for real world building applications.

I remember reading an article that teaches how to use the precision that Blender already has and making the most of it because if you use Blender units you can assign to them any arbitrary value that you want and what I mean is that you can take Blender units and assign a value of a foot (or meter) for example but you can assign a different value so a Blender unit can be an inch or a centimeter and when you do that you effectively change the precision range of Blender and that allows you to design parts with it with a greater degree of precision.

I found it, here is the link to those tutorials:


A 3D modeling program such as Blender is really a very flexible tool with many uses, you have found it useful for sheet metal unfolding and there are plenty of other uses for it.

I could easily design a house with it with more than enough precision for real world applications (actually it is far more precise for that than it is for the creation of a bearing because the margin of error of such a large object in the real world is much wider) but by changing the value of the Blender units you can have more than enough precision for smaller things as the tutorial explains.

Of course CAD tools such as Inventor and Solid Works have special tools and methods that allow faster creation of such things and much easier editing of things already created but that doesn't mean that you can't create a lot of real world things with a 3D modeler, there is plenty, plenty that can be done with them and many people think that they are only for cute 3D models and animations, hell no! A lot can be done with them.

Wish I had such powerful free tools as Blender, The Gimp, Inkscape and the like when I was 10 years old, I would have put them to good use since then!