Prusa i3 z height adjuster

thingiverse

This easy-to-print accessory attaches to your Prusa i3's bottom left motor mount with an M3x40 screw. It features nut traps at the top and bottom, allowing for flexibility in placement - shown is an M3x40 with a nut in the lower trap secured by a spare spring. Alternatively, locknuts and thumbwheels can be used or you could get creative with your preferred setup.