While I agree with sheadunne's quote, I note that the more specific rules for potions, scrolls and wands all indicate
[URL said:
http://www.d20pfsrd.com/magic-items#TOC-Magic-Item-Creation[/URL]]The creator must have prepared the spell to be stored (or must know the spell, in the case of a
sorcerer or
bard) and must provide any focuses the spell requires.
However, for items like Wondrous Items, where it is clear co-operative work is accepted, the reference is still to the creator:
[URL said:
http://www.d20pfsrd.com/magic-items#TOC-Magic-Item-Creation[/URL]]If spells are involved in the prerequisites for making the item, the creator must have prepared the spells to be cast (or must know the spells, in the case of a
sorcerer or
bard) but need not provide any material
components or focuses the spells require.
Now, the material components also are not needed for wondrous items, where they are for wands. hmmm...
[URL said:
http://www.d20pfsrd.com/magic-items#TOC-Magic-Item-Creation[/URL]] You can create a
wand of any 4th-level or lower spell
that you know.
Emphasis added. Scroll and potion have the same phrase, and the Potion FAQ makes it clear that the brewer must know the spell - the prereq cannot be ignored. It does not address a second character providing the spell, though, and scrolls and wands don't tag similar errata.
However, wondrous items (and, I assume, the other feats) don't refer to spells you know, and sheadunne's quote refers to "prerequisites", which are listed for wondrous items, arms & armor, etc., but not for wands, scrolls or potions. I don't think these more simple items have prerequisites, so I think the creator of the object cannot get around the requirement that he know the spell by calling a friend.