The structure of the Grabber Reacher is made from PVC pipe. We choose 1/2 inch PVC for the arm after simulating many different options of extruded materials for the arm under a 2lb (8.9N) load.
We simulated 3/4" PVC, 1" PVC, Extruded Aluminum, and 1/2" PVC Pipe. The 1/2"PVC was strong enough and much lighter than the 3/4" PVC and 1" PVC though very flexible. The extruded aluminum was much less flexible but would have been harder to machine, and harder to assemble with the PVC handle.
The bulb pump on the handle has two check valves on it to pump air from the outside into the soft robotics gripper.An additional magnet was added to the gripper to allow it to pick up metal items. The air bulb in the handle has only one moving part. This makes it simpler to manufacture than a mechanical trigger linked to a piston such as a bike inflater. In addition, the air bulb with check valves requires multiple squeezes to grab something so the gripper can have a large volume difference and relatively high force.
There is a hole in the tube connecting the bulb to the gripper to let air out to release the gripped object. The hole can be sealed with a thumb to keep grabbing something. This is much lighter and simpler than a push button release.
The 1/4" inner diameter tubing was chosen because it could fit on the air bulb and was relatively inexpensive. The tube could only be ordered in bulk so we had extra to use even if the inner diameter was larger than necessary to transfer the air.