Blender has several different file formats that you can export your surface model to.
Now I'll give you some basic ideas for exporting and importing into Pepakura. Although these instructions are written for Blender, these steps should work with pretty much any modeling program.
Blender offers the following export file formats:
3D Studio (*.3ds)
AC3D (*.ac)
Autodesk FBX (*.fbx)
COLLADA 1.3.1 (*.dae)
COLLADA 1.4 (*.dae)
DEC Object File Format (*.off)
DirectX (*.x)
LightWave (*.lwo)
Lightwave Motion (*.mol)
M3G (*.m3g, *.java)
MD2 (*.md2)
OpenFlight (*.flt)
OpenInventor (*.iv)
Quake 3 (*.map)
Raw Faces (*.raw)
SoftImage XSI (*.xsi)
Stanford PLY (*.ply)
VRML97 (*.wrl)
Vertex Keyframe Animation (*.mdd)
Wavefront (*.obj)
X3D Extensible 3D (*.x3d)
xfig export (*.fig)
Pepakura Designer allows the opening of the following file formats:
Pepakura Designer File (*.pdo)
Hexa Great (*.6kt, *.6ks)
Wavefront (*.obj)
AutoCAD (*.dxf)
Metasequoia (*.mqo)
3D Studio (*.3ds)
Lightwave (*.lwo)
STL (Binary format) (*.stl)
Google Earth (*.kmz, *.kml)
Looking at these export and import file formats, we notice a couple that are similar.
Wavefront (*.obj)
3D Studio (*.3ds)
Lightwave (*.lwo)
These three surface model formats are quite common and are supported by both programs. Therefore, exporting in one of these three model formats should result in a working importation into Pepakura. Now remember: if the model doesn't work very well in one file format, you can always try out another. It doesn't hurt to experiment with the different formats to see which one works for you.
In my case, I prefer 3D Studio.
Export the model, save it to a folder where you can easily find it, and then simply open it with Pepakura, following the simple instructions to set up the model orientation. Then unfold.
It's that easy!
I'll be writing up a tutorial with images here soon to explain the process in a bit more detail.
Until then, happy armoring!
----------------------------------------
EDIT: Tutorial now posted with step-by-step instructions:
Tutorial: Blender to Pepakura