This is what we use for waterproofing our fireworks before a display. It's clear, so you can still see through it; we also like to use fluorescent post-it notes where the fuse is so we can see it clearly. Extended core rolls mean they are straightforward to hold whilst wrapping, making the process easier.
The price is for a single roll 40cm wide, a massive 300m long, so it lasts ages!
We wrap our cakes in both directions meaning a double layer of protection. The fireworks will easily burst through the plastic, but remove the wrap before firing if you would prefer.