Z-motor brake for Ender-4, that prevents build plate from sinking, when power is off.
(A version for other printers can be found at https://www.thingiverse.com/thing:3466178)
Brake arms are mounted floating, so there should be no influence on printing quality.
1 x Z-Motor Mount.stl
1 x Break Shaft Lid.stl
1 x Break Shafts.stl
2 x Breake Arm.stl
2 x M3x25mm
2 x M3 nuts
1 x Spring of some kind, that pull the brake arms gently together. Only a low force is needed.