Magnets are great for temporary signage. Although typically used for vehicle doors they can also be stuck to any metal surface. 

We also can make fridge magnets that are great for promotional purposes.  All of our magnets are made out of 0.03" thick automotive magnet material. Most vehicle magnets are 12"x 24" but they can be made to any size. 

We can put a 1 colour vinyl on it or a full colour graphic.