Monoprice MP Select Mini Flexible Z Coupler

thingiverse

The Human Coupler efficiently transmits motion up and down the rod without inducing unwanted Z-axis wobble in prints. It achieves this by allowing the top and bottom of the rod to move freely, preventing movement transfer. A distinctive cup-like shape at the rod's base provides vertical support while permitting smooth sliding motion. The design eliminates the need for nuts, screws, or straps.