Simhopp's belt tensioner was a little short for my belt and the idler pulley was lower than the original. So I modified it. I also made it two pieces so it could be installed without taking the frame brace off. I reused the two original bolts and nuts, but you still need a bolt for tightening.
Update: 10/10/16 Minor dimensional changes to make things go together easier.
;Basic settings: Layer height: 0.2 Walls: 1.6 Fill: 40
;Print time: 54 minutes
;Filament used: 3.145m 9.0g
;Filament cost: 0.18 / 914.36