ok i'm a total newb at everything; i just want a good simple 3d object modelling program that best allows me to unwrap or unfold - not to apply textures for gaming but for cad in making 2d patterns of 3d surfaces. all i want to do for example is come up with 2d patterns which will build a sphere of specified size - say, 2 metres in diameter. this problem is driving me crazy. every program out there is for gaming, or for engineering drawing or animation, and they all touch on unwrapping but won't derive 2d patterns easily. i know i'll have to be dealing with polygons rather than exact spheres - that's no problem. i will gladly tattoo the username of whoever can help me onto my left bicep so that the world can see it next year when i compete in the octagon. just kidding but i'd really be grateful

I am not sure I understand what you need.
You want to create something in 3d then unwrap the 3d mesh to 2 dimensions? What for? I need some examples to understand.
I know a lot about unwrapping for texturing purposes but it's first time when somebody asks about creating 2d patterns for cad.

If you can give me an example from life what you need it for, I will try to help.

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Andyba, 3d artist
skills: 3d modeling, texturing, rendering, 3d character animation, compositing
3d software experience: 3ds max, Maya, Softimage XSI, Deep Paint 3d, Body Paint 3D, Wings 3D, Z Brush
2d software experience: Adobe Photoshop, Adobe After effects, Macromedia Flash, Freehand

i want to upholster an object defined by a customer - say, a weird looking chair. I design the chair using a 3d modelling program, the program explodes the object along seams i define to create 2d patterns i can output to a plotter. i cut out the pieces in fabric and upholster my chair.

I recommend standard unwrapping procedures, then rendering the UV template. Many applications (Blender, Maya, Max, Softimage, Modo, Silo, etc) allow you to do this quite easily, check Google & help files. Blender has a built-in feature that does it, and so does 3Ds Max, I know that for a fact, just look around on the help sites (In Max, just open the Unwrap dialog again after you finish your 2D layout and go to tools->Render UV Template).

You'll also be able to specify what kind of seams you want rendered and which you don't (like the ones outlining polygons, for instance).

Render it out as a raster file with a really high resolution, whatever 3D app you're using. Afterwards, convert it to a vector file using whatever tools you have or find online. Illustrator does it, but it's commercial. Try something like Inkscape, it should have the feature (I can't guarantee it, though).