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 made this spacer so the damper can be used without altering or vandalising the stepper motor in any way.
To mount this thing to your Ender 3 (not Pro) printer you need to move both the Y-axis endstop and stepper-motor-mount to opposite sides (mount from left to right, endstop from right to left). Mount the spacer and damper to the stepper motor (remember to run the belt throught before bolting everything together). And mount the whole thing to the motor mounting plate.
I reused most stock-parts, but you are left with 2 stepper motor screws and 2 endstop bolts as they need to be replaced by 2 M3x25 bolts (actually x23 so i cut 2MM off) for the spacer and 2 M4x30 bolts for the Y-axis endstop.
Make sure that after mounting it, the belt is still centered and please check belt tension.
In the pictures I used rings for spacing the endstop. I have made a printed spacer for this now.
I have also designed a solution for the X-axis, see https://www.thingiverse.com/thing:3271077
I suggest 100% infill for all parts as I always print structural parts solid, but if you are as lazy as I am and want to shave a good hour off your printing time, using 70% is pretty sturdy also. I don't know what the minimum infill can be, but remember you want to secure the bolts tight without crushing your print, and you don't want any play in your printer.
If the size of the spacer is somehow off, you can always use the original spacer plate I remixed to shim it into the perfect position.