So I wanted to print out rhmorrisons snap on rack (http://www.thingiverse.com/thing:22292) but couldnt fit it on my print bed. So I designed a smaller one, but used his wheel that holds the bearings.

So.. print two of each... get some threaded rod that is at least 5" long and 4 nuts that thread on to the rod. I used 1/4"-20

Put them all together like in the pictures.... and there you have it! I have found that a clip on the rod under the feeder, with the filament feeding through it helps keep the filament from spitting out filament excessively.