Mine came this way, but it has pieces of sheet metal on the inside of the styrofoam to finish it. You might be kinda of limited as far as what you can add due to weight. Do you have a sectional door? Is it wood or metal?
A unique option might be to use cloth, but have it themes (i.e. flags, T-shirts, etc) to something you enjoy. It would be cheap and light weight and fairly durable.