My son jumped on our Burley Bee and broke the round tow bar part of the flex connector (the part the anchors the bike to the trailer). It was a pretty simple design so I created a replacement part solely in Bambu Studio's slicer. There is plenty of torque applied to the tow bar so print includes 6 walls and 50% infill for strength. PLA and PETG both shatter under the strain of riding, but I have found success in using Priline's Flex TPU 98A.