This is an upgrade for the Tronxy X3/X3A's pathetic Y axis. It is listed as a work in progress but it is currently installed on my X3 and works very well.
You will need two 400mm linear rods and four LM8UU bearings.
Use this for the tensioner:
I added a rod holder with an integrated end stop. It works fine but I'm still not happy with it. It may change in the future.