How do I make a crossbow?

2. without codding it is actually impossible... 

But you can try that way

https://mcreator.net/forum/91242/custom-bow-tutorialcode-forge-1182

1. just use the item representation model of the crossbow (i dont know if that exists in every version)

2. make an animated texture and trigger a texture change with the trigger "when item is used" (i recommend tagging it so it wont do that with every item)

for #3, i made an item, then added a method for 'when right clicked' that first checked an nbt I named 'isLoaded' and shot the gun and set the nbt false if it was true, otherwise it would wait an amount of time and check if what was in the main hand was the item. if true, it would set the nbt 'isLoaded' to true and removed an ammo. the one thing with this is that you dont need to actually keep anything during the wait to finish loading the gun.

Do you have any image of how to do that?

the simplified version of what I did is.

if (Get NBT logic tag "isLoaded" of Provided itemstack) do {
	Shoot (Arrow of type <whatever projectile> ...) ...
}
else if ( <ammo> = item in off-hand of Event/target entity ) do {
	Wait [number] ticks then on server-side do {
		if (( <weapon> = item in off-hand of Event/target entity ) && ( <ammo> = item in off-hand of Event/target entity ) do {
			Shrink item in off-hand of Event/target entity for [number]
			Set NBT logic tag "isLoaded" of Provided itemstack to true
		}
	}
}

this can obviously be changed to look for the ammo anywhere in the inventory, or to cancel the loading if it's interrupted, but that's something you can do.

Is there an chance that you could export your procedure?

I can export the procedure, but I'm not sure how to link a download for it, much less if I'd be allowed to do so. I'm also not sure I'm allowed to post images either. :/