This changes the end pieces from http://www.thingiverse.com/thing:515131 but the remaining pieces are identical.
With this version, the bearing is totally enclosed so it doesn't matter how you pick it up, it doesn't fall apart.
I made the pocket size for the bearing to be 22.1 mm and for me this made the bearings a pop in/don't come out fit. If you'd like something sightly larger, let me know and I'd be happy to create a larger version.
jb035 made a narrower version here
Uses skateboard bearings (608 - 22mm OD, 8mm ID, 7mm thickness).
I used 5/16" wooden dowel as the shaft.
The .fcstd files are FreeCAD files (created using the linux version 0.14)
I used six #4-40 x 3/8" flat head screws to hold it together, although I imagine that M2.5 x10mm shoud work as well.