1. This is the most important step. If you are using plastic chargers, spray them first with Primer made for Plastic!! I made the mistake the first time of using regular primer. That does not work with plastic! If you use primer for plastic -- your chalkboard paint will stick.
2. Spray your chargers with Chalkboard Spray Paint. You can find it at your local hardware store - like Home Depot.
Some other ideas:
Fourth of July
Another chalkboard paint idea --
These can be used over and over!