The use of robotic systems for harvesting of crops is a growing application domain in the agriculture sector. A key challenge is to develop robotic systems to harvest soft fruits such as raspberries which require delicate handling as they are easily damaged. Designing and optimizing a robotic harvesting setup by testing on real raspberry crops can be challenging due to the short natural harvesting period and the cost and logistical challenges of running experiments in the field. To solve this problem, we present a sensorized physical twin of a raspberry which can be used to develop robotic harvesting systems before deploying in the field. The sensorized raspberry has the capability of measuring the applied forces before and after it has been picked off the plant with a high sensitivity. The mechanical design was optimized and a material with properties similar to the real fruit was chosen, in order to achieve similar mechanical properties to a real raspberry, specifically the stiffness before and after picking and the pulling force. The paper concludes with a harvesting demonstration performed by a robotic gripper, where the sensorized raspberry is used to assess the quality of the picking action. This work aims to lay the groundwork for accelerating the future development of robotic harvesting systems to enable robust development in a lab before deployment in the field.