Why throw out those old ammo cans when you can find a new purpose for them! You can do tons of cool things with them. I turned the ones we had at the shop into donation boxes but you can turn yours into a suggestion box, jewelry box or just keep it an ammo box but make it look nice!
Step 1: Start Out by Sandblasting
First you need to sandblast off any rust or remaining paint from the cans and lids. This leaves you with the raw material and a nice surface for the powder coat to stick. Then you need to drill a hole in the can where the lid comes down to create the waterproof seal so you can use an eye bolt and lock to secure your can closed.
For mine I milled out a slot in the top for the donations to go through.
After your desired holes or slots are made you need to give your cans a chemical bath to ensure there is no grease or finger prints that will prevent your powder coat from going on evenly. Be sure to wear gloves because these chemicals can be rough on the skin. I used TSP for my chemical bath.