Belt tensioner with 624 bearings
thingiverse
I modified the belt tensioner to use a couple of 624 bearings. Instructions This a drop in replacement for the belt tensioner in makealot's http://www.thingiverse.com/thing:11601 Print out and assemble thing:11601 Print the stl file and fit 2 624 bearings and swap with the exitsting tensioner. You may need to drill out the holes to an appropriate diameter. I've included the modified scad file in case you prefer to use another sort of bearing.
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