While the cardboard pieces are drying, you can cut out the fabric. You will need 1 of piece A, without the tabs. 1 of piece B without the solid tab. You will need 2 of piece C, 1 with the center circle and tabs removed, and 1 with the center circle not removed. Put aside the fabric with center circle not removed for now.
Glue the fabric to cardboard pieces. Be careful to not get the glue on the outside of your fabric. Wait till everything dries.