Thomas Kumlehn of Pixel Partner sent me a nice email regarding the iPad Chair. He did a roughly similar Instructable to mine on an iPad 3-D viewer. This is another laser cut flat-pack iPad holder, but this holds the iPad in the perfect location for viewing stereoscopic 3D images and video. He uses a readily available lens the redirects your vision to over under pairs. The iPads portrait mode works very well for this.
I remember as a child, a friend had a vintage side by side stereo viewer with a bunch of black and white pictures for it. I remember how amazed I was by them.
He has files available for cutting on his web site.