I wish make a real sofa can be as cute and as easy like this!
This is how to make it:
Cut the box and foam into 4 pieces (0r five if you want the doll seat to be double layer): the biggest one is for the doll seat, one for the back part and two similar pieces for the arm.
Cover all the pieces using fabric. I dont sew any of them, just glue.
Fold the arm part and glue it. Glue all the pieces together.
For the coffee table, I use the cap of my betadine mouth wash and cap from my body cream. Glue them together.