Triskelion Design

This is a version of an ancient Celtic design called a Triskelion. I saw this design when I was in a museum in Berlin, and snapped a photo with my cell phone. It's a challenging, but fun design to figure out how to make. I feel like I'm connecting with really smart artists from a long time ago when I play with this design!
Can you figure out how I made it? The construction animation will show you how I made it (show all first), but maybe you can find a better way!