I think it would be interesting to make 'Salutes' like the instructions to recreate the old M80 firecrackers with flash-powder.
I have read lightly about the legality of this stuff, it seems you can be licensed by the ATF ( it is set up as a Shall-Issue ) to manufacture and store explosives provided you have them inspect and verify you have the proper 'magazine' for storage.
Is there anything you can do by-the-book ( as in you can't be sent to jail etc ) firecracker wise? I think you can mess around with black-powder cannons with no worries provided you have the space to fire one. Are black powder salutes vanilla?