Simple is always best. I use paper strip that go from pole to pole all around the fuse, from the fuse down to the south pole. I cut them only as long so they don't overlap at the bottom, eliminatig paper buildup. The last strip is pasted on the south pole to fireproof the small part that has been left unpasted (because the strips dont overlap on the bottom).
Sure, kid blows his fingers off using "Armstrong's mix" and the media put a gigantic headline on the front page saying "Child loses fingers while making fireworks". Then the anti fireworks people go into a frenzy demanding the banning of all fireworks claiming they are a menace to society. At which point the politicians see political points up for grabs and bang, there comes another legislative paper tightening the grip on sale and usage of fireworks. Oh, and matches will probably get banned somewhere in the process.
Also, might it be an idea to spray/coat shell casings with a resin (to water proof) and then a tack glue (left partially to dry), and then dip into a bucket of finely grated paper machie/wall paper paste slurry?,...a frame could be made to accomodate to hang many hemisphers at once to dry at the same time,...they could then be re-dipped in the slurry to achieve required thickness.
This will hardly provide any stenght, you need long oriented fibres to give the casing strenght, paper mache will provide no such thing.