I love the Y Belt Tensioner by freemark! It has two screws for Y Tensioning. This allows for slightly angling the pulley left or right to line it up just perfectly. I added some thumbwheels, washers, and lockwashers to lock it all down. I had a spare piece of plastic that I used between the frame and screws to prevent damage or cracking.
However, I knew there had to be a more elegant solution. This Y Belt Tensioner by Audiogod is pretty sweet for those that prefer the one center screw adjustment (doesn't allow for angling the pulley just right). If I did prefer that method, I would definitely print this one.
That said, I transported over the bar Audiogod developed which was very nice and spreads the force out over a larger area. It was a bit too big for this mod, so I cut it down a bit to allow the bracket to slide in and out without rubbing.
Here it is. All credit please to Audiogod and freemark!
I printed with a Brim of 4 Lines just because it's long and thin and could curl on the ends. I printed with PLA 188 degrees with a bed of 60 degrees on BuildTak. Came out real nice.