If you're on a big project where you're using cleaners and epoxies, can you stow these in the gangbox? No, you need to store them in special containers designed for flammables storage.

The rags you use when working with solvents become flammable vapor sources and kindling. These require special containers for storage/disposal. The typical flammables container is unbreakable, with a flame arrester and a spring loaded cover. It's also color coded; that's why kerosene cans are blue and gasoline cans are red. Use the right kind of container for the flammable you're storing; read the MSDS to determine what that is.

In addition, don't store flammables near corrosives or oxidizers (see MSDS of each chemical). Nearby corrosives might eat the container from the outside while oxidizers might cause it to erupt in flame. For example, don't store solvents in a battery room. Escaping fumes can travel along the ground to ignition sources hundreds of feet away. Close container lids tightly, and provide ventilation per the information in the MSDS.