Why does Jack Sparrow look for the actual key to Davy Jones' chest instead of trying to recreate it?

Question

Dead Man's Chest has Jack Sparrow carrying out the following plan, in precisely that order:

1. Steal the drawing of the key to Davy Jones' chest
2. Locate and steal said key
3. Retrieve and open the chest

Now if for some reason the key cannot be forged again, that makes a lot of sense. But for a complete ignorant of blacksmithing like I am, it doesn't look that complicated a metal shape to reproduce:

It would seem much less risky to steal the drawing, retrieve the chest, and then settle down somewhere and try to re-create the key. Holding fort is easier if it's on land, since Jones can't come ashore. I can see two obstacles, but also an attempt at overcoming them:

• the drawing isn't a 1:1 scale. Fiddling with sticks of various lengths could give you a better idea of the key's actual length.
• no forge/blacksmith available. I don't know if Tortuga has a forge, but it doesn't seem that much of a reach. And if it boils down to blacksmith's skill, Jack gets a pretty talented one quite soon, when William Turner meets him again.

Out-of-universe it wouldn't be very thrilling to watch pirates elsewhere than sea, trying out different metal molds, but in-universe it sounds way safer. Why wouldn't they do so?

Answer 1

I think the unique design of the key combined with the fact that there was magic involved stopped Jack from duplicating or making a new key. He had the "drawing of a key" and theoretically could have had somebody make one for him, but again: A McGuffin does have to be there,if it begins to exist. I think maybe Jack didn't know anybody to make a key or even didn't trust anybody to make a key, which is more likely. Or the lock could have been imbued with some sort of magic? It's unclear, but I think most likely Jack didn't trust anybody to make him a copy without telling Davy's men. Jack Sparrow trusts nobody, not even himself.