Step 1: Tools and supplies
One cardboard box large enough to fit over the costumee's torso
Six round craft boxes - We used 7" boxes but depending on the size of the wearer or the type of brick you are replicating you could go smaller or larger.
Hot glue gun and glue
Duct or packing tape
Step 2: Find an appropriately sized box
As an after thought, our box seems to be made of thicker cardboard than your standard moving and storage box so if your box seems a little flimsy you might want to think about reinforcing it on the inside with thin strips of a light wood or cardboard using hot glue.
Step 3: Find round boxes for the studs
We didn't use the lids so we are saving them for a project to be determined later. We did talk about using three on the back of the costume to make it look like the underside of a LEGO brick but since the costume was already finished by the time we thought of it, we decided against it.