Custom magnets stick to anything with steel or iron in it: fridges, filing cabinets, whiteboards, metal doors, tool chests, and most car body panels. They will not stick to wood, glass, plastic, drywall, or aluminum. Not sure about a surface? Hold a fridge magnet to it. If that sticks, your custom magnet will too.
Surfaces that work
Anything with steel or iron works: fridges, filing cabinets, whiteboards, metal doors, tool chests, lockers, and most car body panels. These give a custom fridge magnet the flat metal it needs to grip, and the smoother the surface, the stronger the hold. See how strong custom magnets are.

Surfaces that do not work, and a quick test
Magnets will not stick to wood, glass, plastic, drywall, or aluminum, since none of those are magnetic. This catches people out with cars, since some newer ones use aluminum or fiberglass. Before you order, hold a fridge magnet to the spot. If it sticks, your magnet will. More on cars in whether magnets work on cars.
Stainless steel, aluminum, and galvanized steel
Stainless steel is the common surprise. Some grades are magnetic and some are not. Many appliance fronts, especially newer fridges, use a non-magnetic stainless finish, so a magnet sometimes will not hold on the door even though the sides do.
Aluminum is not magnetic, so a printed magnet will not stick to aluminum panels, window frames, or aluminum car bodies. Galvanized steel is just steel with a zinc coating, so magnets still hold. With any metal, the fridge-magnet test settles it.



