Patent ID: 8449345

Claim:
A set of building blocks comprising: a first piece (P 1 ) having a flat plane (S), a top side ( 34 ) and a bottom side, wherein, at a center of the top side ( 34 ), a V-shaped groove (G) whose two surfaces (Ga, Ga) are tilted symmetrically from a reference plane (H) orthogonal to the flat plane (S) or a plane (S′) including the flat plane (S), an angle formed by each of the two surfaces (Ga, Ga) and the reference plane (H) being approximately 45 degrees, and whose bottom (Gb) extends parallel with the flat plane (S) is formed, wherein the first piece (P 1 ) is in a doughnut half shape, the V-shaped groove extends in an axis direction of the doughnut half in the uppermost of a top side ( 34 ) thereof, and a recess ( 36 ) of a semi-circular column shape is formed at a center in a width direction of the bottom side of the first piece (P 1 ) in the axis direction of the doughnut half; and a second piece (P 2 ) having at least a corner edge (A) to be engaged with the groove (G) of the first piece (P 1 ), so that one side (Af) of the corner edge is brought substantially in face contact with the V-shaped groove (G), wherein a first width (WS) of the flat plane (S) is greater than a second width (WG) of the groove (G) along the direction perpendicular to the reference plane (H), and a center of the first width (WS) of the flat plane(S) is coincided with a center of the second width (WG) of the groove (G).