One of the key challenges in soft robotics is the development of actuators which are truly soft and compliant, and can be adapted and tailored for different applications. In particular, the development of untethered soft actuators could enable robots to autonomously explore the world in an unrestricted manner, exploiting their compliant behavior. In this paper we present a method for creating fully soft, degradable actuators where the actuation of the system is controlled by setting physical parameters which 'mechanically program' the actuator determining the characteristics of the actuator. The actuation process is driven by the release of gas from a reaction between a bio-compatible acid and base. This approach allows for the creation of fully untethered actuators which could be deployed for use in agriculture, to make ingestible robots or to allow untethered exploration. This paper provides the 'recipes' for the development of the actuators used, and the methods for mechanically programming of the actuators. © 2020 IEEE.