1.21.8 skript HELP With custom entities

[Injoyed]

I am working on a script that will allow me to throw an snowball with another texture the issue is I have tried almost all ways with this like using itemtype expressions but nothing is working my code for this shows what I want:

on projectile hit:
if projectile is a snowball:
if metadata "Special" of projectile is "JoyBall":
broadcast "Works"
on right click holding a heart of the sea:
make the player shoot snowball at speed 0.5
play sound "minecraft:entity.snowball.throw" at pitch 0.33 at the player
set item model of shot projectile to "minecraft:slime_ball"
if name of player's tool is "&aJoyBall":
set metadata "Special" of shot projectile to "JoyBall"

What I want it so edit the texture of the snowball to a slime_ball but it doesn't work
the error is ->
[23:12:20 INFO]: Can't understand this condition/effect: set item model of shot projectile to "minecraft:slime_ball"
[23:12:20 INFO]: Line: set item model of shot projectile to "minecraft:slime_ball"
[23:12:20 INFO]:
[23:12:20 INFO]: Encountered 1 error while reloading ball.sk! (17ms)

[IMPORTANT] I would like to know how to change an entity texture that is all due to everyway not working

 

[Injoyed]

Does anyone know how to change an entity's texture? any addons for skript will do.