Soandso activates his recipe to create Robes of the Archmagi in an area with all the required workbenches (in this case, a Fabric and Leatherworking Station and a Magician’s Workbench). He has the Craft Wondrous Item feat as well as all materials that are needed, so his crafting screen opens. However, while Soandso has the recipe and materials, he is a sorcerer and did not choose Spell Mantle from his spell selection list. So he gets Tharianis, his wizard companion, to provide it for him. His Craft: Tailoring & Leatherwork skill is high enough to always match or beat the skill check, so he provides that himself.
After taking all the necessary steps on his crafting screen, Soandso initiates crafting. Both the skill check for Tailoring & Leatherwork and the Spell Mantle spell power DC are passed succesfully and the item is made. Now the crafting fatigue penalties are handed out. Soandso provided the skill himself, so he also pays for that himself. Soandso has a base constitution score of 14 and a dexterity score of 16, so he is given a 50-2-3 = 45 fatigue penalty. Tharianis cast the needed spell, but it was Soandso who was the craft master providing the Craft Wondrous Item feat, so that penalty goes to him as well. Another 50-2*2 = 46 penalty.
He started out crafting with 0 crafting fatigue, but now he has 91. More than enough to be applied the harsh penalties of being badly fatigued for many weeks. He did get a magical item of awesome power, but he might have been a lot better off if he had found another to supply the Tailoring skill. Or he could have given his recipe to Tharianis to make him the craft master instead… if he was willing to take that hit, possibly for a handsome fee.
Dispater