Glue Something to cut with (x-acto knife) Any Gundam 1/144 scale kit Female Disconnects 22-18awg (pictured to the right) Pliers
First remove the metal ends completely from the Female Disconnects 22-18awg. The easiest way is to twist them out with a plyers.Here you can see a few that have been separated
Next determine how far out you want the shoulder to stick. Why, because we are going to be cutting the connector so that we can attach the joint
Next, take your Gundam kit. They come with softer plastic connectors that act as the joints. Select one of these and glue it to the end of your cut connector. Here you can see a connector that I hot glued to a Gundam joint. To add some stability to the two parts. It also wouldn't hurt to cut off a spur, or small shaft of plastic to stick between the two parts before glueing.
Next, attach it to your shoulder parts and you are ready to go.
Some different angles of the shoulder joint and arm.
The easiest figure to use this on is the Acroyears. Here is a figure I attached it too using an Acroyear chest torso.