I love my Shure e3c sound isolating earphones, the sound quality is great, the durability of the cord is phenomenal. I have had them for years, they are my go to earphones when traveling, or working with noisy equipment.  I was disappointed when I accidentally broke the tube off when working in the shop one day. 

So I designed a repair part that bonds onto the earphone and provides the tubular mounting feature that the soft earpieces slip over.  The repair slightly increases the length of the earbud, but the length increase is required to create a large enough bond area for a strong bond joint.  I tend to used the very small ear adapters and I did not notice any change in comfort level after repair.  The sound quality seems as good as before as well.

I used a "gel" type cyanoacrylic adhesive (a.k.a. super glue) and it seems to hold well.  An epoxy would also be a good choice if you stay away from the quick setting types.  I cleaned the earphone end using an acetone wetted paper towel.

This repair may work for other Shure models that use the same adapters.

The repair parts are made from ABS, using an FDM 3D printing process.