I bought some stepper motor dampers for my Creality Ender 3 3D printer but they wouldn't fit because my stepper motors have press-fit pulleys (which are hard to (re)move).
For the Y-axis, I recently made a spacer (https://www.thingiverse.com/thing:3245255) so the damper can be used without altering or vandalising the stepper motor in any way. I wanted a way to use a damper for the X-axis also, so I have adapted the original Ender 3 X-axis motor mount plate to accomodate for a damper without changing the location of the stepper-motor (and keep the pulley in the same place).
To mount this thing to your Ender 3 printer you need to replace the original x-axis motor mount plate with this one, and also replace the x-axis endstop cover with the one I have designed. You could use the original endstop cover but you need to use a spacer and longer screws so the endstop is in exactly the right position again. (Or take a saw and shorten the original cover and screws by 6mm ;-) )
I reused most stock-parts, but you are left with 2 long stepper motor bolts which need to be replaced by two really short M3 screws to mount the damper to the stepper-motor.
Make sure that after mounting it, the belt is still centered and please check belt tension.
Also very important: you need to have dampers with the correct hole diameter so they fit over your pulley (see pictures for correct model.) The first ones I received had a 14mm hole which was too small. The second set I received has a 17mm hole and fits perfectly. If you have the wrong dampers you have to remove the pulleys (and if you could do that, you wouldn't need this fix at all ;-) )
The mount plate must be printed at 100% infill. This is a structural part and must be as strong as it can be. Also use supports so the gap where the damper sits is printed OK.
For the endstop cover I used only 20% infill as it is not a structural part.