This is a remixed version of https://www.thingiverse.com/thing:2780420
I really liked this carriage, but I found that the tension wasn't enough to take care of slop in my x-carriage. So, I set out to make this adjustable. You will need some M3x20 screws and nuts to use with this carriage. It has worked great for me. I used the small lock washers on the wheels to put enough of a gap between the carriage and the extrusion. With all this my X-Carriage is rock solid and moves on the rails easily.
Supports are built in to the model, and hopefully will be easy to remove for you.