This is a remote-controlled airplane bomb that I designed using Fusion 360. It requires 12 magnets of 3x2 mm, which can be fixed in place with just quick-drying glue. You also need to print two halves of the bomb components to assemble it completely. In the future, I might design an automatic dropping mechanism for it.

Put flour inside the bomb. When you drop it from a remote-controlled plane, the bomb will burst instantly after landing, raising a cloud of white smoke.