I've been working on doing my own custom shells. In the process I destroyed one of my balanced armature drivers while soldering. So I decided to take a shot an fitting my MH1c's into the shells I made. Luckily for me, I have large diameter canals and given how small the diameter of the MH1c is, I was able to put the driver close to the tip of the shell. I used heat shrink tubing to seal the driver against the tip. Here's a pic. They sound great. Plan to put on the faceplates tonight.
Congrats on your ingenuity! It actually looks quite good!