Recently, a friend asked me how I did the border on the St. Michael icon. I wanted to say, "Very carefully," and leave it at that. But she is a fellow iconographer and deserved the long, complicated answer.
The Michael icon is largely an experimental one. The border is just one of many different techniques I tried for the first time.
As far as the border is concerned, the difficulties included, first of all, painting on gold leaf (a metal) with a water-based medium. Imagine trying to paint your car with water colors. Secondly, there is working out the pattern I used and transferring it to the gold leaf. Thirdly, there is the actual painting of the pattern.
I based the pattern on the Zentangle® pattern XYP. Scroll to the bottom of their newsletter to see the step-out.