A series of plastic building block pens, made of smooth plastic, with rounded bumps and grooves on the top and bottom of the blocks, which can be nested and connected to form a stable structure. The edges of the blocks look rounded and there are no sharp parts, which reduces the risk of children getting injured during play. These blocks can be used alone or in combination with other types of blocks or toys to increase the variety of play. The sides of the blocks are serrated, which can be closely connected with other blocks to increase the stability of the structure. While being used for writing, it is also interesting and can increase children's interest and hobbies.
