This is a cool tin...with marshmallows inside! The tin is metal, with slightly raised/embossed Sonic design. Its odd shape is formed after the image, making the tin quite a unique piece. A metal tin makes sense for marshmallows: something which can go stale easily. As you can see here it's sealed with anti-tamper plastic, as it is a food product. This can be found at Forbidden Planet in Birmingham. It costs about 2.99 pound. It is only about 4 inches long. The marshmallows have an artificial strawberry middle.

They aren't reported to be the best quality, but really you are after the tin anyway. 

Photo by Shadouge