I did it on my Kaufman Cascades quilt. Here's a link.
My version of Kaufman's 'Cascade'
I preserved the whole rhomboid-or tumbler-on the top and bottom (or sides since the thing was square). I used a bias binding and sewed to the front, then hand stitched to the back. The angles were pretty easy to navigate around. It took a couple of 1st's at the local fairs a couple of years ago.
Bias binding--there are a gazillion ways of doing it but I used this method
https://so-sew-easy.com/making-conti...-binding-tape/
Have fun!