Additional Hardware needed:
https://www.amazon.de/dp/B0859BQSQW/ref=cm_sw_r_apan_glc_i_B8XNFC8FBQN778B8AE2E?_encoding=UTF8&psc=1

You'll need 26 of these links + the two end pieces for z axis.
If you want to add the x chain as well you'll need one more cable end cap and a mount for the moving part of the gantry to mount the other end of the chain to. As this is very individual I have added the fusion file for the adapter X end cover to x chain so you can edit the height according to your needs. This adapter can then be bolted to “X end cover new” with up to 3 M3 bolts.

The lower base for the z chain features a small hole in case your fit is too loose. You can tap this hole and add a grub screw to it (see last picture)

UPDATE 06.03.2022:
Added a x end cable chain mount for the stock ender 3 carriage including a picture of how to mount it (CAD screenshot, last picture).
A Updated Fusion360 model has been added as well (Ender 3 z cable chain adapter 06.03.2022)

Happy printing :)