Zuesad,

Welcome!

Wow, that is an AWESOME jacket!  I can see why you like it.

Making a pattern for that is complex, since it doesn't seem like a repeating skull pattern. It might be, but what I can see in the picture is too small to show repeats.

You could start with a very plain sweater pattern and chart a bunch of different skull designs based on the number of stitches in the pattern. This will be complex, but I can't think of a way to do it while designing a jacket, too.

The other thing you might be able to do is make the jacket, then cross stitch various skulls on it. Even better, if you know Tunisian crochet, those stitches are great for cross stitching over them.

Hope that helps!