Cotton fabric pouches with built-in hanger. Fill them with your favourite potpourri blend, with or without essential oils. They can then be hung in a closet or bathroom cupboard, or hung from your vehicle's rear view mirror.
Suggested fillers include lavender blossoms, rose petals, wild clover, cinnamon sticks, cloves, cedar leaves, spruce needs, juniper berries--or other naturally fragrant materials. Add your preferred mixture to some baking soda or scent-free kitty litter and enhance with essential oils if desired. Fill your pouch through the partly opened seam, then sew the opening closed with a thread and needle.