Paint all toilet paper rolls black and let them dry completely.
Cut bat wings and ears from black cardstock. Each wing should be about 12 cm wide with curved tips, and ears about 3 cm tall.
Glue the wings to the back of each toilet paper roll and attach ears at the top.
Stick googly eyes on the front and draw small fangs with white paint or a marker.
Punch a small hole through the top of each bat and thread twine through to hang them. Space them evenly for a balanced look.