Just so that he could get a good idea for what he wanted that Wood-Giant to function like, Eisen started using his visualization in a slightly similar way to the manner that he tried to gain as much proficiency as possible in his crafting space and crafter's mind skills.
But instead of actually physically trying to make a 'double' of himself create items, he just wanted to pretend as if that was the case. He basically just wanted to go through the whole process of building that wood-giant for now. And since Eisen didn't want to practice actually making it just yet, he didn't use the deep visualization state. That would require him to already know how exactly he wanted to do.