This stand was tested for iPad2
Due to different dimensions and weight it doesn't work for all models (it's not stable in all positions). Rail is made to snugly fit iPad2 shape.
Inspiration ? http://yohann.com
(sorry but it's not available yet and a bit pricey for me :/ )
I added magnet in the back for bluetooth speaker, which (if mounted) increases stability in some positions, but decreases it in others.