sugru user Carson just posted this fantastic project on gurus showing how he molded a precise new strain relief for his cable using a 3D printed mold.
"A clumsy seat-mate on an airplane broke the audio plug on my earphones when he was trying to get out of his seat. I was able to remove the existing overmolded strain relief and resolder the connections, but I was left without a strain relief. I used some heat shrink tubing for a while, but was unsatisfied with the appearance.
Here's how I did it:
1) I used 3D CAD software to model up the strain relief geometry for the audio plug. 2) Using the original CAD as reference, I then created CAD for a 2-sided mold for the part.
3) I printed the mold parts out in a 3D printer (polyjet). 4) Needed some mold-release chemicals to allow the parts to come out of the mold, like greasing a cupcake tin. Didn't have any mold-release handy so I used olive oil. 5) Mold the Sugru around the bare audio plug by hand, while properly aligninge plug into the mold. 6) Close the mold with a C-Clamp and remove excess squeezed out of the mold. 7) 30hrs later, Done! Open the mold and enjoy the new overmolded strain relief I created!"