In looking at your web site and the enlargement of the Beltany Ring, it appears that Denise has used strips of fabric that are cut between 1/4 - 1 inch(some may be wider). The strips are cut straight and with curves, and then layered to give the dimension that you are looking to achieve.
I would guess that she has used a muslin for a backing piece and layered the strips on top using a fusible which would hold them in place until she does her quilting. If a fusible is not used then there are many who use glue sticks to attach the fabric until the quilting can be done.
However as others have pointed out, it will be the overall use of your colors of fabric that will give you the best dimension.
These are fabulous quilts and yours should be wonderful when it is done.
Happy Quilting,
Susan