I buy the boxes made for fridge/freezer use. You tear the sides of the box off and there is a fine mesh that keeps the baking soda in the box but provides more surface area to absorb (adsorb?) odors. Just open it and throw it in the bag/container with your scent free clothes.
I used to pour a regular box of baking soda into a black sock and keep it in my bow case to help eliminate odors. Also, you can use it to pat yourself down.