  Bio-inspired soft robots have already shown the ability to handle uncertainty
and adapt to unstructured environments. However, their availability is
partially restricted by time-consuming, costly and highly supervised
design-fabrication processes, often based on resource intensive iterative
workflows. Here, we propose an integrated approach targeting the design and
fabrication of pneumatic soft actuators in a single casting step. Molds and
sacrificial water-soluble hollow cores are printed using fused filament
fabrication (FFF). A heated water circuit accelerates the dissolution of the
core's material and guarantees its complete removal from the actuator walls,
while the actuator's mechanical operability is defined through finite element
analysis (FEA). This enables the fabrication of actuators with non-uniform
cross sections under minimal supervision, thereby reducing the number of
iterations necessary during the design and fabrication processes. Three
actuators capable of bending and linear motion were designed, fabricated,
integrated and demonstrated as three different bio-inspired soft robots, an
earthworm-inspired robot, a four-legged robot, and a robotic gripper. We
demonstrate the availability, versatility and effectiveness of the proposed
methods, contributing to accelerating the design and fabrication of soft
robots. This study represents a step toward increasing the accessibility of
soft robots to people at a lower cost.
