DEER is a creative modular toy set designed for children aged 4 to 6, developed under the theme of 'Serious Play.' The project aims to foster imagination, spatial awareness, and early analytical thinking through hands-on construction play. The system consists of colorful straight rods in various lengths that can be connected using angular corner pieces at different fixed angles. These components click together with a satisfying tactile feedback, allowing the child to intuitively explore form, balance, and structure. DEER is not just a toy—it's a tool for open-ended play. It steps away from repetitive or overly prescriptive sets and invites the child to build, break, and imagine freely. With the slogan 'Deer, Play, Cheer!', the product brings joy and development together in one flexible system.