Step 1: Acquire Materials
1) two plastic containers from the inside of a Kinder Surprise Egg (or whatever else you have lying around that you can poke holes in, fits in your shoes, and can open/close)
2) a couple spoonfuls of baking soda
3) two tea bags
4) two small safety pins (or staples)
5) a thumb tack
Right... onto the construction!
Step 2: Fill the Tea Bags
If you need, grab a funnel and fill up the now empty bag with baking soda. The baking soda is the active ingredient and soaks up the nasty odours from your shoes. You can also add other scents by adding them with the baking soda. I just went went with baking soda because my philosophy is that the only thing worse than the smell of sweat in a locker room is the noxious mixture of Axe AND the smell of sweat in a locker room :P Same goes for my shoes.
When you're all done filling it, you need to close the bag back up. I used a small safety pin to close it , but you could just staple it back together.
Step 3: Make Holes!
And of course, be careful to not poke yourself.
Step 4: Assemble
You'll have to change the baking soda every so often to maintain the freshness, but that shouldn't be a problem because you can just pop open the Kinder Surprise containers and change out the tea bag.