Once you remove the Symphony I and compare it to the RNS-E, it is obvious you need to trim some off the bottom. I used a hacksaw and a lot of elbow grease. Once you remove the bulk of it, start off with some rough sandpaper and smooth it out, then finer sandpaper to finish it off. Make sure to protect the screen when you have it laying on its face.
I have not added the side inserts yet, but they can be made from the bottom once it is removed.