Jellycopter

Thanks!

I'm not interested in doing anything in public.  It's more that I'm wondering what I'm allowed to build i .e what technically qualifies as an illegal explosive (or similar dangerous device) and what doesn't.  
Can you do anything at all without an explosives certificate?  I was interested in making my own electric matches and triggering system, but with no target explosives - like this  

I don't have any proper training, and it seems pretty difficult to get on a course without some kind of professional justification, unless the course is just about basic safety rather than designing pyrotechnics. 

I'd be interested in the firework books you mentioned?