Print in flexible material. for diameter 1" & 0.060" (25.4mm, 1.5mm) thick steel tube often used for poles on trampolines. I used 1.5mm2 cable through it but use any type of cord that will fit... Use many layers when printing to get a strong part. I used my own TPU filament material but it contained lots of moisture thus the rough surface on the picture... http://rubber3dprinting.com/