For someone who has say leather working or painting tools, what would you use to roll on to determine how good the item is? If you trying to evaluate how beautiful the workmanship? 

Performance, or something else? I see performance first, since like a musician showing their skill with that, making a beautiful leather pouch is similar. Or is it something else in other cases?

Is it just a straight Int or Charisma check instead?

For quality, a dex or int (tool) check, for artistic appeal, probably cha(tool).  Performance for when you want to entertain people.

If you're proficient in the tools you're using, then you add your proficiency bonus from the tool, not from any skill. "Making things" is probably almost always an Intelligence check, though I could definitely see cases where Dexterity would dominate, especially with really fine detail work. I really don't buy Charisma as being applicable to any kind of creation roll.

Performance is not a "creation" proficiency. It should never be applicable to the production of goods, art or otherwise.

I could see Dex as the default attribute for using most tools, but I think it is fair to consider intelligence and wisdom as contributing factors.  An intelligent (N)PC might figure out how to do something they haven't done before and a Wise (N)PC might know what they have learned from experience.  Charisma is already built into many skill checks and unless it is fashioning a piece to attract the interest of a particular target (a single person, or Elves, or Nobles of Royal Family, ...) I would not think Charisma has much to do with it.

Quote from SagaTympana >>

If you're proficient in the tools you're using, then you add your proficiency bonus from the tool, not from any skill. "Making things" is probably almost always an Intelligence check, though I could definitely see cases where Dexterity would dominate, especially with really fine detail work. I really don't buy Charisma as being applicable to any kind of creation roll.

Performance is not a "creation" proficiency. It should never be applicable to the production of goods, art or otherwise.

 I would use charisma for trying to make art, as it's less about the technical ability and more about the ability to move people's emotions.

Quote from Lunali >>

Quote from SagaTympana >>

If you're proficient in the tools you're using, then you add your proficiency bonus from the tool, not from any skill. "Making things" is probably almost always an Intelligence check, though I could definitely see cases where Dexterity would dominate, especially with really fine detail work. I really don't buy Charisma as being applicable to any kind of creation roll.

Performance is not a "creation" proficiency. It should never be applicable to the production of goods, art or otherwise.

 I would use charisma for trying to make art, as it's less about the technical ability and more about the ability to move people's emotions.

Eh, I thought about that and dismissed it because once we're discussing "moving people's emotions" we've beyond the actual creation, so it's really a second subsequent roll. Making something is simply a fundamentally different thing from trying to use something to convey meaning or feeling. They're definitely related, but the actual "making" aspect is infinitely more related to "mental acuity" than to "your ability to interact effectively with others" (descriptions taken from the PHB). I'd absolutely require Intelligence to determine quality and I could maybe accept Charisma to see how well it conveys its intended message. A high enough roll on the first could confer advantage on the second, because there is a relationship. But they're still separate tasks.

I wouldn't use charisma. Your personality doesn't have as much impact on what you can produce compared to your knowledge and ability. Historically, some of the greatest artists were poopy people or insane.

I think it would depend on the objective of the die roll.

However, I can see a justification for using charisma for the creativity element of art work. Intelligence and wisdom could both be important. Intelligence to figure out your subject, the lighting, the angles .. wisdom perhaps in terms of intuition, laying out the scene or knowing your subject matter. On the other hand, charisma could be used for creative element, coming up with a piece of art that "speaks" to those viewing it, which carries a message and has an impact beyond just being a pretty picture.

Most creative activities though would seem to be a combination of physical and mental effects. Designing and building a gadget or trap could be dexterity and intelligence. Similarly, creating a suit of metal armor might be a combination of strength and wisdom ... strength to manipulate the metal and wisdom to know exactly when to stop working it. On the other hand, the initial design would likely be related to intelligence if the design was created by the blacksmith forging the item.

So depending on the item being created there could be two checks involved ... one for production and the other for "effectiveness" or "design".

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INTELLIGENCE
Intelligence measures mental acuity, accuracy of recall,and the ability to reason.

INTELLIGENCE CHECKS  -  An Intelligence check comes into play when you need to draw on logic, education, memory, or deductive reasoning.

WISDOM
Wisdom reflects how attuned you are to the world around you and represents perceptiveness and intuition.

WISDOM CHECKS - A Wisdom check might reflect an effort to read body language, understand someone's feelings, notice things about the environment, or care for an injured person.

CHARISMA
Charisma measures your ability to interact effectively with others. It includes such factors as confidence and eloquence, and it can represent a charming or commanding personality.

CHARISMA CHECKS - A Charisma check might arise when you try to influence or entertain others, when you try to make an impression or tell a convincing lie, or when you are navigating a tricky social situation.

I cannot agree at all with the charisma thing. I've seen far more emotional pieces from quiet and reserved people than from outgoing, commanding people. 

We've had this discussion before. I say let the player determine the stat they use with the tool proficiency. If they can come up with a good description of how they use X stat, then it's all good. If they're trying to justify calligraphy(STR) they need a damn good reason, but no harm in letting them try. You can always just stare them down if they're obviously reaching.

It's their character. Let them decide how they do things. There are lots of different kinds of PCs and they would not all tackle the same tasks the same way.