Nothing's impossible
In July I made a rash statement that making a heart shape out of a single rocket shell was impossible (fake fireworks). I still think the display in question was a fake but it seems that it is possible to get the parts of a shell to explode with a heart shape, at least that's what Graeme Anderson photographed during a fireworks festival in the Hague. In the original post I actually said that a flat heart was impossible in other words the parts spread out horizontally rather than falling, this one doesn't look flat. Computer generated displays can of course be programmed to act like real projectiles as in the computer generated display below, however I prefer the real thing as in the second clip. An analysis of this motion would be a great idea for an investigation or EE.