You can take 10 when you make a skill roll "When your character is not in immediate danger or distracted".
Would this include when a character is making a magical item?
There is a nice discussion of this very topic here.
You can take 10 any time you are not rushed or distracted. It counts as your one roll and takes no extra time. Use this when an average roll should suffice to let you succeed, but a low roll would fail.
On the other hand, Take 20 is something to choose only if you have enough time (takes 20x as long), and when there is no significant penalty for failure (you take all penalties before you are successful).
Taking 10 and Taking 20 - from d20pfsrd
The real question is whether you have enough ranks and skill points to beat the DC for your magic item with a 10 - easy to do with lower CL items, of course.
you can take 10 on that check under normal conditions.
As opposed to taking 20, because in that case there is the additional requirements that the performed check must bear non consequence on a failed test. On the specific topic of creating a magic item, failing the check by 5 or more results in a cursed item.
This has been confirmed by a developer at Paizo message boards:
Are you able to ‘take 10’ for crafting magic items?
Yes, as long as you're not distracted or in immediate danger.
The take 10 mechanic is in the game to prevent characters from being punished by the randomness of a d20 roll on a task that should be routine.
I feel like my players who are doing crafting are getting it very easy. There is no chance for them to fail their crafting attempts at all.
That is intentional--as long as they're picking items for which they meet all the prereqs, they should have no chance of failure.
While Sean K Reynolds is no longer a developer at Paizo, he was at the time of writing that message.