Its a shame we can't get fireworks over here - they used to be fun - but sadly like morons with lasers shooting them at planes, they've been banned - probably because parents didn't supervise kids with them, which lead to blown off fingers/burns/injured pets. Not to mention people blowing up neighbours letterboxes!
What I used to do was take one of the big sky rockets, tape po-ha's to it, and light the po-ha's and rocket at the same time (aerosol can and a lighter). The rocket would go up, banging along the way as the po-ha's exploded, and usually the rocket's display piece didn't work right because the rocket had holes blown in it
Another trick was to cut wings/rotor blades from an ice cream tub and attach them to a catherine wheel. Drive a nail through a bit of wood, an put it on the ground, pointy bit up. Sit the catherine wheel on it, light it off, and it would quite often (if the wings were angled right) turn into a giant ufo or bumble bee (the things you lit on the ground and they took off into the night sky with a whiz.)
The last trick (and this one is super dangerous, don't try this at home!) would be to get a couple of packs of the grey sparklers, wrap them in foil then 2 or 3 rolls of electrical tape. Stick it in a hole in the gound, and one sparkler would be the fuse. Light it and run like buggery. It would either turn into a massive spakler fountain or (more often) explode with a earth shaking kaboom. FSSSSSSSHHHHH KABOOM!
That last one you could easily devistate a letterbox with because it easily made short work of dead whitegoods!