Congratulations you’ve made it to the toughest thing of 4 in 1. expansion and contraction and seams are very similar. But instead of doing it one row at a time which can get hard to track on larger pieces. The seam allows you to easily join pieces like a sleeve to a shirt easily.

I am using the Low carbon steel 15ga 3/8 OD ring for this.

First off lets make some small pieces to join.

You can make you pieces as big or small as you want. it won’t change anything.
Starting from the bottom or top doesn’t make much difference. For this tutorial I’m starting at the bottom.

Let’s start with joining the pieces together with a single ring looping into a ring on each piece in the second row.

From here on you will be looping into three rings. the ring you added last and a ring from each side.

looping all 3 rings can be a little difficult at first but once you understand what’s needed it’ll start to go smoother.

You made it. You’ve mastered European 4 in 1. Don’t stop honing your skills. Try European 6 in 1 or the dragon scale.
When you plan to use this for a shirt take your time when sizing your pieces. Finish your arm hole then figure out how many rows you sleeve will need to be. Otherwise you could be having to take the sleeve apart to add or remove rows. And there’s nothing worse then getting a piece half attached and finding its wrong.