These designs are released under the FreeBSD Documentation License.
Screws into the screw holes holding the Xtion's case together, and mounts on the PR2's head using the 25mm bolt pattern.
Download: Google SketchUp ColladaXtion snaps into the top, and a 1/4"-20 nut snaps into the bottom.
Download: Google SketchUp ColladaScrews to bottom of FitPC. Since the FitPC gets quite hot, this should probably be machined from metal rather than 3D printed.
Download: Google SketchUp Collada