Yep that's how they did for me. (Well, one is a masker but same thing) They mix up a compound and put a bit into your ear just at the beginning of the canal. It only takes a few minutes to set up. Then they send that off with the specifications you need for a hearing aid, and the lab puts the electronics into the ear piece. You go back another day when it's done, and they make sure you know how to wear it, and that it works right for you and fits. And they teach you how to change the batteries, and to clean it.

I need to do this again.. it's been 10 years and wayyyy overdue. TC!