i liked the Sleeve Case for Raspberry Pi B+ from walter.
http://www.thingiverse.com/thing:604915
My Pi is not lying around 24/7 so i needed a way to fix the pi into the case.
I added two half buried screws on the bottom. After assembling you just have to screw them in and the pi + case is fixed.
I used little TX6 lens head screws (2.5x10)
| Raspberry_Pi_B+_Sleeve_v1-1_CAP.STL | 133.2KB | |
| Raspberry_Pi_B+_Sleeve_v1-1_VENTED_Screws.stl | 200.3KB |
