How do create flying debris like in movie posters?

[voidsource]

Hello everyone,
my problem that im having is that i want to make a really cool movie poster ( for learning purposes ) and I have seen that lately the trend is to have sparks and debris flying around. Ill link 2 examples. but my only problem is that I want to learn to make the debri and not just dl a brush and use the brush. I am one of those people that sometimes wants to learn how its made. With that being said here are the 2 links:

Olympus has fallen

captain america poster

can you guess give me a clue as to how they achieve this? i would assume some part is to go into brush presets and use scatter or jitter. but not really sure how to make it :/ thanks in advance.

[KTG]

Re: How do create flying debris like in movie post

Wouldn't you know it. There is a debris brush:
http://www.brushking.eu/227/debris-brush-set-.html
Google Flying debris in Photoshop and you should get other links or tutorials.
k

[voidsource]

Re: How do create flying debris like in movie post

thanks for the link but mostly google searches return with pre-fab brushes; That's good and all but I would really like to know how to make my own.