Looking back for some guidance from long ago...
In one of her DVDs or photobooks (with DVD attached) Airi pays a visit to, I think, a workshop of her grandfather. I have looked and looked but I can't find it. Can anyone remember this, and which DVD or PB it was, please?
EDIT: Aha, found it already... it is [2012.07.25] Koko ga Suki, from around 4:30