Magic Item Creation - Pausing for Special Components

Question about Magic Item creation:

If a magic user is creating an item, the spell effect is in his spellbook, but he does not have a formula or sample of the item. So, he gets 50% complete and then learns he needs special components that he does not have.

Can he pause the item creation at that point to do something else, wait until he has the components, then pick it back up with only 50% to go when he has the components?

Edit: Replied in wrong thread