I was reminded of the things we used to do to produce duct transition layouts and such in the days before TC got unbend and unfold, and even now if you're trying to lay out a compound surface reduced to polygons. Some people used to use card model software like Pepakura, I moved on to a program called UltimateUnwrap3D, which is quite inexpensive but works really, really well. I just had a search for interest's sake to see if there's anything new and found a program called dxf2papercraft on Source Forge, an open source project to do this task. It doesn't have a graphic interface, it's command line only, I downloaded it and had a bash, and it works as advertised. Puts glue tabs on the edges of facets, paper model fashion, and suppresses them if they overlap. I don't know how many faces it can handle at once yet, more experimentation needed, but a useful string to add to the bow. Any more than 10 or so faces to flatten manually, and I get real bored, real quick.