Structure for coupling assembly blocks

A structure for coupling assembly blocks of a polyhedral shape formed of a plurality of side plates, a top plate, and a bottom plate, the structure comprising:

• a first coupling member formed on a portion of a first outer surface of at least one of the plurality of side plates, the top plate, and the bottom plate;
• and
• a second coupling member formed on a portion of a second outer surface of at least one of the plurality of side plates, the top plate, and the bottom plate other than one on which the first coupling member is formed, wherein
• the first coupling member of one assembly block is configured to couple with the second coupling member of other assembly block in a sliding manner, in a fitting manner, or in a rotating manner,
• the first coupling member includes at least two first protrusions formed on at least a portion of the first outer surface and a groove between the two first protrusions,
• the second coupling member includes a second protrusion formed on at least a portion of the second outer surface,
• the second protrusion is configured to slide into the groove when coupling one assembly block to other assembly block,
• each of the first protrusions is formed with a cross section in a tapered shape expanding outwards,
• the groove is formed with a cross section in a tapered shape expanding inwards,
• the second protrusion is formed in a substantially spherical shape, and
• the second protrusion is fitted into the groove when coupling one assembly block to other assembly block.