"It’s because it is for the wedding," Alice explained. "Neville was discussing it with Frank this morning, when they were looking over the design plans. He and Harry were up late into the night assessing the Ritual Chamber and Harry’s Alchemy Cell, eventually deciding that neither one was powerful enough for this sort of wedding ceremony. So Harry spent the rest of the night perfecting plans he had been working on for a new one, then began construction as soon as there was light to work by. I have a feeling he used his time-turner extensively to get it right, because he looked like he hadn’t slept in a week, Nev told me."