Designing a self-defense weapon hidden in an everyday object involves many considerations, including legality, safety, and ethics. Here are some tips and considerations: 1. **Legality**: Before considering designing a self-defense weapon, be sure to understand the laws and regulations of your country or region. Many places have strict regulations on the definition, carrying, and use of self-defense weapons. 2. **Concealment**: Some everyday objects can be used as self-defense tools, such as flashlights, umbrellas, or pencils. These items will not arouse suspicion under normal circumstances, but can be used to protect yourself in an emergency. 3. **Safety**: The designed self-defense tools should be safe to avoid accidentally hurting yourself or others. 4. **Practicality**: Make sure the designed tools can effectively protect yourself at critical moments, rather than just for psychological comfort. 5. **Training and preparation**: Understand how to use the designed tools and consider relevant training to improve efficiency when using them. In short, although some everyday objects can be used for self-defense, you must be very careful when designing and using them to ensure that they are legal, safe, and effective. If you have a strong need for self-defense, it is recommended to consult a professional or take a self-defense course.