So you peaked my curiosity and I just had to go out and do some work. I pulled the form out and made the rings. I laid in the ring and it looks like it's going to be about at it's deepest point 14''L X 9"W X 12"H. Here's where you come in, I need you to convert this to cubic feet for me
. Now keep in mind depending where you decide to trim the form, you can add and decrease the volume.