Ammo Can Before Camouflaging
First, chose your ammo box carefully. Reject those with dents and large scrapes. If all the boxes you have to choose from are dented, try to pick out the ones that are not dented on any of the corners or edges. Those dents can make for weak points.
Second, open the box. If it's clean and still smells of oil, then the seal is still good. Check the latch and make sure it holds the lid tight. Don't be bashful in the store, you're selecting a game piece for who knows how many players.
Do the sanding outdoors if at all possible. Sanding will stir up a lot of dust and it will settle everywhere. Wear a painter's face mask to prevent inhaling the stuff. (Otherwise, besides the health concerns, you wind up with green nose hairs. Hah!) You may also want to wear some disposable gloves. Take off the lid and sand it and the box thoroughly. Get all the lettering and rust off of the box. I use a Black & Decker mouse sander. Cheap and does a good job. Get up under the handle and don't miss the welds and hinges. Wipe the dust off with a dry disposable cloth or paper towels.
Turn the box upside down, and hang the lid up (I hang it from a tree limb out back), and spray evenly and lightly with paint primer. Let dry for about an hour and then spray again for good measure. Let dry overnight.
I like to go to the location where I intend to place the cache and take a picture with a digital camera. I do this to capture the colors and textures of the hiding spot. You know, leafy, dirt, lots of green, that kind of stuff.
At Wal-mart, Kmart, and Army/Navy stores you can find camouflage paint for reasonable prices. Select at least two colors, a primary and a secondary, based upon the colors of the intended hiding spot.
The primary color is the most predominant color. The secondary color is the less dominant color. Say the area has a lot of tan with some green, tan is your primary and green is your secondary.
Take the box and turn it upright, with the lid off. Spray about a 3 inch band around the top using your primary color. Wait for the paint to dry thoroughly and reattach the lid to the box.
Now spray the secondary color first all over the box with a nice even light coat. I may apply a second coat for lighter colors.
Then spray the box with the primary color making sure to hit the hinges, latch and all the corners and main edges. What you're trying to do it break up the straight edges so that they are not so prominent. Don't spray as if you were doing a second coat. Just do portions making sure that your secondary color is visible in proportion to the colors of the intended location. Try to mimic the textures if you can. Twigs? Vines? Stone? Try to match.
Spray right over the handle and latch. When the paint is dry, lift the handle with a toothpick or twig and spray away the "shadows." The same goes for the latch.
Let the box dry at least overnight. Turn the box over and paint the bottom being sure to continue any patterns you have on the rest of the box. The point, as I said, is to break up the outline of the box.
If you mess up, don't worry about it. Let the paint dry, sand it off, and try again.
This is, in a way, an art form and each person does it a different way. I've had people standing in the woods next to one of my boxes for a long time before they spotted it. I know then that I've done a good job!