Patent attributes
An assembly unit includes a side plate having a plate shape and including a first coupling member on first side, a second coupling member on second side, and a third coupling member on each of third side and fourth side, a top plate having a plate shape and including a fourth coupling member on each side and a top stud on the top surface, and a bottom plate having a plate shape and including a fifth coupling member on each side and a bottom stud on the bottom surface. The first coupling member includes a protrusion. The second coupling member includes a groove. When the first coupling member of the side plate is engaged with the second coupling member of a neighboring side plate of the same type as the side plate, the protrusion of the side plate is fitted into the groove of the neighboring side plate.
