When Isis took over the highchair, Electra needed a booster seat so she could sit in one of the big chairs at the kitchen table. We put together a big fat cardboard book for her to sit on. We found a box with a Japanese castle on it, so you could even say this seat is throne-like.
I sewed an elastic band to keep the pages from opening up when she was getting into and out of the chair. The beauty of it? It doubles as a leaf press!