I also used ideas from Exploring Dimensional Quilt Art by C June Barnes. I didn't do the quilted shapes but used an idea for one piece. She explains her designs and the maths involved and they can be adapted to free motion sewing.
The idea was to make two identical circles, cut a slit in each one, then join them together. I didn't quite follow the instructions but came up with something that could possibly be found on a forest floor.
I wasn't sure how the non circular piece would come out once off the hoop but it turned out ok.