In addition to Lamina Design, another one to check out is Pepakura Designer:
http://www.tamasoft.co.jp/pepakura-en/

It can take polygon data in a similar way as Lamina Design, looks like it supports OBJ, 3DS, LWO, and STL formats all of which are supported by MoI. I'd recommend trying OBJ format, but I'm not sure if it supports multi-sided polygons or not. You may need to adjust the option when you export from MoI, from Output: N-gons (which allows many-sided polygons in the generated OBJ file), to Output: Quads & Triangles (which only allows 3 or 4 sided polygons in the generated OBJ file).

- Michael

Lots of people are using Pepakura - then printing and cutting out the parts. They then assemble them, and coat them with Resin to make large sized parts. Here's a link to a Halo fan site with information on Pepakura fabricating:

405th.com

Hi Michael, Alcides and Kurt,

Many thanks for your congratulations regarding the birth of my son. It is hard work but worth it all when he smiles :)

Thanks also for the responses to my questions. I have just tried blender's unfolder, which I'm probably not using correctly. I unfolded a simple cylinder. It made some very strange decisions regarding the unfolding, creating lots of little shapes. From experience, I know that Blender and I don't get on so I'm downloading Pepakura. Thanks Kurt for the tutorial link.

Michael, is MoI able to constrain a surface so that it is forced to be "developable"? For example, I'm thinking that for the sides of a hull, I could lay down an oversized flat surface, adjust it to fit the curvature I require and then trim the excess to abutt adjoining surfaces (did that make any sense?). Then, if I'm understanding what Alcides has said about Rhino, I unroll my surfaces (or perphaps a selection of surfaces?) rather than unfolding entire polygon meshes?

The Pepakura demo has just installed. Time to see what it can do...

Hi Mark,

> Michael, is MoI able to constrain a surface so that
> it is forced to be "developable"?

Not in a fully general manner - for example there is not any kind of "force to be developable" checkbox that you can set.

However, I suppose it would be possible to enforce this yourself if you stick to only a few specific tools and operations that create developable surfaces.

Extrusions should be ok, also probably a sweep of a line segment along a path may do that. You may also be able to edit the points of an extruded surface (see this FAQ question for how to turn on points for some objects) and still maintain developability. You may need to use some kind of surface analysis tool to examine the Gaussian curvature of the surfaces you are working on to make sure they are developable.

In general though that is a pretty specialized requirement, MoI is not focused on that particular area of specialized modeling so if you need to create only developable surfaces you will probably be better off using a tool that is more specifically designed with that in mind - MoI's toolset is focused on much more general shapes.

If you convert to polygons though, that simplifies things a lot and you would be a lot more free to use any tools that you want in MoI and then send the polygonized output to one of those programs (Pepakura or Lamina Design).


> Then, if I'm understanding what Alcides has said about Rhino,
> I unroll my surfaces (or perphaps a selection of surfaces?)
> rather than unfolding entire polygon meshes?

Yes - if you wanted to work in this way you could use Rhino's "UnrollSrf" command which is able to calculate a 2D pattern from a developable surface (and only from developable surfaces). That is an alternate possible way to approach the problem rather than unfolding polygon mesh data. But in general you should probably expect to spend quite a lot of time learning many details about developable surfaces if you want to go this route, it tends to be more used by people who are going to construct their final object out of sheet metal.

- Michael

Funny i have found this today :)
http://www.papermodelers.com

Hi Michael,

Many thanks for the tips. I'm going to have a go at this over the weekend if the boy will give me time. I'm going to try to do this initially in a developable way I think, more in keeping with the actual material. My thinking is that a hull is basically a cylinder shape at midships and various tapers or cones towards bow and stern, trimmed to conform in the horizontal plane (that probably didn't make any sense either!). I will still have to do the unfolding from a polygon model as I don't have access to Rhino. Even so, I'm guessing I'm going to get a cleaner unfolded shape by staying as close as I can to a developable surface.

> Not in a fully general manner - for example there is not any kind of "force to be developable" checkbox that you can set.

Would such a check box be a possibilty for a future version of MoI?

Hi Mark, it sounds like you're on a good track for trying it out anyway!

> Would such a check box be a possibilty for a future version of MoI?

It's not really too likely.... This is a pretty specialized area and it is not an area that I personally have a whole lot of particular experience in. So it just is not really a great match for MoI.

Also it is a big goal for MoI to stay simple and easy to use and understand. Each kind of specialized option that gets added in will have a tendency to clutter the UI and make it incrementally harder to understand for someone who doesn't need that option. There can actually be negative consequences to adding in too many things, that's something I am pretty worried about in general.

- Michael

No worries Michael. I fully understand your concerns regarding feature creep.

I have been playing with export of a hull form to obj and have been reminded of how good the polygon conversion is. I'm quite confident this can be done with a bit of careful design and selective mesh unfolding.