ok. i've found a glitch for cloning fireworks without clone.
when you light fireworks and then send them in and out of a set of portals you'll notice that the fireworks are not lit up and may be used over and over as long as you put it back through
This is also something I found ages ago but didnt say anything.I think the way portal works is it delates the item and remakes it so it looks like its transfering.And the glowing firework is just another form of the element firework.