spawn firework
quicksave

open up the json / quick save

replace
"EntityDefinitionId": "name of firework",
with
"EntityDefinitionId": "Special_Shell_Tim",

then quick load

file location
C:\Users\User\AppData\LocalLow\Laumania ApS\Fireworks Mania\Blueprints
user is pc name :)

bam instant tim
(you can do this to more fireworks)