I want to share with you a way that I find more pleasing in adapting M42 lenses on NEX. Here is a picture of two adapters
Left: regular M42 to NEX
Right: Konica AR to NEX + M42 to Konicar AR adapter
The two may end up to be about the same height but I find the Konica AR setup to be much handy in NEX and the setup match well for my focusing style with small m42 lenses as in takumar and Russian pancake. In preparation with Lens Turbo, I just got my SuperTak 35mm f/3.5 and here is how it looks
And a similar setup with Russian Industar 50-2 50mm f/3.5, an M42 pancake
The M42 to Konica AR adapter can be found in ebay but I just take a look in ebay it is priced crazily in the $80. I paid about $30.00 and it turns M42 lenses for Konica AR mount allowing me to use the smaller Konica AR to NEX adapter.
Konica Praktica M42 Lens Adapter 2 AR