I use the spray stuff to decorate at work. There is a glass door which I turn into a Victorian Lead Window (something along these lines)
and as people come into the building, they look throught the snowy window to the lit Christmas tree next to the staircase. Trying to stop colleagues turning on the overhead lights is a nightmare!! I'm trying to create a look here, people and fluorescent lighting isn't part of it!!!!!!!!! They're getting the hang of it now, thank goodness!!