I found K&J magnetics through Google:http://www.kjmagnetics.com/They have a huge selection, and I settled on their D32 3/16" disc magnets, which are 3/16" tall.http://www.kjmagnetics.com/proddetail.asp?prod=D32I got a pack of 100, ...
27 3/4" clear acrylic cubes are drilled with 108 3/16" holes, fitted with 108 D32 neodymium disc magnets with proper polarities facing out from each, and assembled into a size-matched magnetic version of the original Rubik's Cube.
Update: Instructables user burzvingion has made a beautiful red translucent dice version of this cube. Make sure you check it out!
Tons more pictures of the process can be seen in
Before I devoted my time to this idea, which came to me while imagining a version of the cube that didn't need the intricate connecting tabs found inside a cube, I checked Google for magnetic rubik's cubes, finding none (though a friend found one (theoretically) available in China by removing the 's from rubik the day before I finished this thing). Then I mocked up a 3D version in Maya to figure out the polarities of the magnets to see if it would remain sound as faces were spun all around. It appeared that it would.