Émouvan is an organ in the body that dictates human emotions.  This specimen suffered from a mutation that creates skin layers that hinder communication with the nervous system and dull emotions.

Many of the 3d models you find in Google 3D Warehouse and Thiniverse will be too complex for folding.

This article describes a technique for reducing the number of polygons in the mesh.  It involves downloading a free program called MeshLab (available for OS X and Windows).  Follow these steps:

1. Download the model in SketchUp format from the 3D
2. Open the model in Rhino, Export the file as a “.obj” file (just as you do for opening it in Pepakura)
3. Open the .obj file in MeshLab and follow the instructions in the above article
4. Save the new/reduced mesh as “.obj” and continue wtih this file in Papakura

With this technique, I was able to take this model of a hand from the Google 3d Warehouse

and reduce it to this:

 Which I was then able to unfold with Pepakura, far more reasonably: