If you have heavy test fishing line you can make your own tubing puller. Just take a piece that is about 10-12 inches long, loop it over and tie it at the end. To pull the tubing through poke the looped end through the earmold from the end that goes in your ear canal, stick the tip of the tubing through the loop and pull it back through the earmold.
Some tubing is too fat to go through the earmold. I try to use the thickest wall that I can so I don’t have to glue it…
The typical size is size 13T or 13TT (super-thick).