If you are one of those who like to experiment with chemicals, smoke, fire and other things (and I think there are many who will say yes) today I bring you a video that you will find very entertaining.
As the title says, it is nothing more and nothing less than how to make a homemade flare. The instructions are in English, so it is not very difficult to follow the steps. The result is very beautiful and eye-catching. And although it is very simple and elementary, I am sure that with a bit of inventiveness you will be able to create something more colourful or complex.
I hope you enjoyed it. If you have any questions, don't hesitate to ask them in the forum.
English 
Spanish
It's a pity that the video is no longer available on Youtube. Can you upload it again? Thanks!
I have the same doubt as DoctorPC, how do I make it last longer, with more chemical elements or with another container?
I wonder how they will do it to last for real flares :S
If you add more ingredients, and apart from the fact that military flares are made of different materials, but if you add a lot more, this is only 5g.