I printed off some fireworks related pictures from Sparklebox (I love this website - in theory its designed for teachers, but it has such great stuff), cut them out, then let Riley loose.
After the printed pictures, I gave him some lick-and-stick stars, and then PVA glue and glitter.
I must be mad!!! I haven't dared go under the kitchen table yet to clear up the excess because I know its going to be THAT BAD! There was glitter everywhere - including on Freya and in Riley's mouth (how, I have no idea). The finished piece isn't the prettiest he's ever produced, but its all about the process and he had so much fun.