This is by far the best Z belt tensioning system you will use. Made for the Kobra 3, this system allows for adjustable tension, and uses proper bearings and a GATES pulley.
BOM:
M5x40 screw Link: https://a.co/d/g06Lm8d
Small M5 screw to hold bottom bearing
2x 695 bearings, at least one has to be flanged Link: https://a.co/d/cCavRbS
9-11mm pulley, 5mm ID Link: https://a.co/d/gVQBXCO
Why is this one the best Z tensioning system? Simple. By using bearings, and proper pulleys, we minimize runout and enhance precision. The biggest feature is using an actual pulley, meaning that we can very precisely drive the Z timing belt while cutting out any chance of slipping.
Assembly of this is very easy. Start by cutting off the small support piece on the top rectangle section. Insert a bearing onto the screw, then slide the screw into the system, whilst also putting the pulley on. Then, install the bottom pulley, and use the small M5 screw with a m5 nut to tighten the pulley onto the plastic part.
I have been testing this system for 3 months now, and have had no issues with it. Part consistency is better, Z layer look nicer, layer lines are minimal, and Z bed probing has gotten much more consistent

