It is a tight fit so it might need a bit of sanding, the 2 i printed to fix 2 mycobot 320pi fit perfectly without any sanding.
I printed one with 20% infill which held up fine, but would recommend to use 100%.
I designed this for the joint 4 so i do not khow if it fits the other joins, but it might fit.
joint_connector.stl | 1.0MB |