Hi, I think the store is called Arribas Brothers, or something like that. If you are heading towards the castle it is on the right side after the side court where they do silhouette pictures.
When my family was there in Oct we went in a few times to watch him make things. At one point we were the first ones there and he started a lid for someones vase. Then we snuck out, or so we thought, to see wishes and came back in to watch him finish it. He commented on how we deserted him for fireworks. By the time we got back into the store he had finished most of it. We thought it was amazing to watch him make such beautiful things.
I went and looked it up. The store is called Crystal Arts.