This is a different approach on how to add a z-axis damper to the  Ender 3, compared to other designs on Thingiverse. I designed it for my  Ender 3 Pro, but it should fit on all variants of the  Ender 3.
This design has several positive attributes:
Sturdy
Parallel to x-axis
Let's you adjust the distance between the motor axis and the 2040 profile to align the z-axis spindle
The whole assembly slides up and down in z-direction and has "tabs" to align it properly with the aluminium profile
Things to know before you print this:
You have to take off the x-axis assembly (no problem)
You need to use the included mount for the z-axis switch (uses M4 threads for the stock z-axis motor mount)
You need 4x M4x10 screws and 4x M4 T-Nuts (I have included a design that accepts regular 3mm thick M4 nuts)
Mounting it should be straight forward, but just in case:
Remove the x-axis assembly, take of the stock motor mount and stock endstop switch mount
Push the print bed all the way forward
Insert the T-nuts and slide the bottom…