Spray your felt all over with the 505 temporary adhesive.
Cover the felt with your scraps of fabrics. You can use any kinds of fabrics: cottons, satins, laces, cheesecloth, etc. Rearrange to create a collaged background you are happy with.
Spray the backs of the fabrics as needed to temporarily secure them to the felt or batting.
Bring to your sewing machine and free-motion stitch all over to adhere the fabrics permanently in place.