I’ve been asked whether it was difficult and how to do it, so I took photos as I went along to post. To start out, anchor the thread (I used Nymo for this) and pick up one bead, stitching back to front. Next, stitch back up through that same bead.
Next to the first bead, pick up two beads and stitch back to front. Stitch up through the last bead only, making a little triangle of three beads.
Repeat this process – pick up one bead and stitch back up through it, pick up two beads and stich back up through the second.
You can use all the same color, or create patterns by using more than one color. I am using dark beads for the bottom of the triangle and a lighter bead for the top. To do this, use color A for the first bead, then color B for the first of the two, color A for the second of the two.
Continue this all the way around.