A coupling for coaches, wagons etc. made from various files grabbed of this site.

Print out on a brim if using a FDM printer and carefully trim away surplus with a sharp craft knife.

The bar may/will need to be trimmed to fit your rolling stock and I've incuded 2 hoops.

I've printed out the long hoop, as in images and will pivot the parts with thin wire, possibly a cut paperclip.

I 've added a wide loop for use on tighter curves.

Creality

Ender 3 Pro

Yes

No

.015mm