I also traced around a music CD.
Then I cut a very small pie slice out of each layer and sewed the cut edges together so each layer was just slightly cone shaped, giving the pad a contoured shape.
I used 4 layers:
Outside layer of PUL (not sure this really ended up being necessary as I wasn't a big leaker)
2 absorbant layers inside: I used 1 of hemp terry, 1 hemp fleece. You can use old t-shirts, old towels, flannel, cotton, bamboo, microfiber, terry, whatever you have that is absorbant.
1 inner stay-dry layer of suedecloth.
I basically just used what I had on hand left-over from making diapers.
I don't have a serger, so I just zig-zagged over the edge several times around to keep it all from fraying. They worked great!