I made this chair for my son, who is nearly 1. I want to make a similar chair sized in three varying sizes for infants, toddlers and little kids.
12mm Baltic Birch. No hardware, the back and seat press through the sides, and then with a light tap slide back and down (seat and back respectively).
Very secure, sturdy and should be relatively cheap.
I am trying to design and line of kids tables, chairs, etc for a local store.