I took a few different colors of cardstock (construction paper works too) and cut out different heart shapes. I did have access to a die-cut machine but don’t let that stop you if you don’t! Hand cut hearts would probably me much more charming!
I sewed through them on my sewing machine with clear thread. Pull out a foot or so of thread before you start sewing so you have plenty to hang your hearts with.
I could never have too many of these hanging around!