All you need, is 3 different looking brooches, you can go any theme, butterflies, flowers, leaves etc.
I chose flowers, so make sure they are more or less similar in sizes, they don't have to be exact, but not too far apart in sizes too, unless you can make it work of course.
Choosing them in similar shades or colours will be better, or else you can just spray paint them. Which on a side note then I would not encourage you to use vintage or expensive brooches if you are going to paint them - just get those cheap ones. I got mine for a few for a couple of dollars.
Then just clip the brooches on a rope/velvet/strong satin ribbon. I chose a pale gold rope for mine [like those they use to make curtain tassles].
Have fun with it and get creative with it! Use ribbons or more brooches etc. [I've actually got 4 brooches in there, I layered 2 brooches in the middle; one on top the other] You'd be surprise how easy it is to make and how it can look really well-done.