The Craft skills is such a broad skill that anyone can become skilled at crafting any material. Even though someone is skilled at glassblowing or armorsmithing, they are not automatically capable of creating special items such as contact lenses or kevlar armor. Some items require a higher technology than is available in most D&D settings. For these items, magic must be involved before they can even be considered.
Creation of technologically superior items are not possible through the use of the Craft skill alone. Spells like Minor Creation, Major Creation, or Fabricate must be involved. Even though a high level craftsman might be able to create anything he sets his mind to, skill alone won't allow for the creation of things beyond his understanding or technology.
A person who uses Minor Creation, Major Creation, or Fabricate must still be skilled at crafting. The main use of these spells is to allow craftsmen to make items without having the tools normally necessary. So a mage who has no knowledge of weaponsmithing would be hard pressed to create a sword for the fighter in the group.
Assume that any piece of work that is greater than what the craftsman can create due to technology restrictions has a DC of 25 ~ 30 when using these spells. Items created in this manner are not considered masterwork items unless the craftsman succeeds at the skill check by 10 or more on the roll. A failed skill check results in the item being unusable as what it was intended for. Failed items may still be useful in some manner. Due to the residual magic left over from the creation of these items, they cannot be used as a material component for spells. This also means that they cannot be used as the masterwork items needed for item creation feats.