Cardboard shipping boxes ... and stick them to each other, then do the same with the other two. Affix one of the rectangle's ...

You will need a hot glue gun, scissors, tape, the boxes themselves ... that will give the cardboard the appearance of wood, ...

A simple cardboard box ... Tape or glue could be useful if your child wants to try some construction. Why not cut pieces of tape and let your child try and stick it in the right place.