AlphaPixel recently delivered a Free/Open Source 3D PDF generation/conversion tool for exporting models to the PRC format and embedding them into PDF files.

Based on an OpenSceneGraph Reader/Writer plugin, and open source PRC code taken from the Asymptote the osgdb_prc plugin converts the geometry, material colors and transparency, and in a limited fashion, the per-vertex coloration of models into a PRC file. This file can be embedded into a PDF file using the libHaru toolkit. The final result is a PDF that can be opened in modern versions of Adobe Reader on any platform, where the model can be viewed in 3D and interacted with.

Read the details here.