Invention Patent for a set of interchangeable blocks, intended to be used as toys, toys for motor development, planning and building skills development toys. The shape of blocks (1, 2, 3, 4, 5, 6, 7 and 8) are based on a cubic shaped block (1), with rounded edges (9), featuring—at the edge shared by two adjacent sides (A and B and / or B and C and / or A and C and / or A and D and / or A and E and / or F and B and / or F and C and / or F and D and / or F and E), perpendicularly to the aforementioned sides—at least one narrow slot (10) with a perfect fit for the partial insertion (111) of the locking disc (11); the said cube-shaped block (1) is also offered as a cobblestone-shaped block (2), scalene block (3), bulged triangular block (4), rectangular triangle block (5), trapezoidal block (6), half cube block (7) and portal block (8).