Assembly unit for toy assembly block

An assembly unit for a toy assembly block, the assembly unit comprising:

• a side plate having a plate shape and including a first coupling member on a first side, a second coupling member on a second side, and a third coupling member on each of a third side and a fourth side;
• a top plate having a plate shape and including a fourth coupling member on each side and a top stud on a top surface;
• and
• a bottom plate having a plate shape and including a fifth coupling member on each side and a bottom stud on a bottom surface, wherein
• the first coupling member of the side plate is configured to be engaged with the second coupling member of a neighboring side plate of a same type as the side plate,
• the fourth coupling member of the top plate is configured to be engaged with the third coupling member of the side plate,
• the fifth coupling member of the bottom plate is configured to be engaged with the third coupling member of the side plate,
• 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 the neighboring side plate, the protrusion of the side plate is fitted into the groove of the neighboring side plate,
• the third coupling member includes a thread,
• each of the fourth coupling member and the fifth coupling member includes a thread corresponding to the thread of the third coupling member, and
• the fourth coupling member and the fifth coupling member are configured to be engaged with the third coupling member in a screwed manner using the threads.