The key to the system is the "U" shaped link. It permits un-coupling and coupling in yards. Practical way freight operation is available
The best source of links are standard staples. They have a rectangular section which permits grabbing with tweezers.
Mak a jig out of 1/8 in thick Plastruct ABS plastic. Drill an .021 diameter(#75 drill) hole 1/8 inch from the edge. Make a groove as shown.
Insert a staple in the hole.
Bend the staple over the jig.
Nip off the long leg at the corner of the bend. Remove the burrs from both ends.
Bend the legs slightly inward. If the link disconnects in a heavy train there probably isn't enough angle.
I tried flaring the ends out for easier insertion. It didn't work. Just leave them straight and remove the burrs.
I use a NON-MAGNETIC pair of tweezers like these. They are the 10" large ones shown with On30 cars. I have tried many types these so far work the best. Magnetic wands and tweezers will not work, the links stick to them like a "booger" on your finger.