I'm building my own observation hive and am curious how others have secured their frames in place. My hive is just a 3 frame high (1 column of 3 frames). Right now the frames rock back and forth between the glass and aren't always centered between the glass. I've thought about building the frames out a bit with some shims to ensure they're properly centered, but then I can't interchange the OH frames with my other hives frames.

How have others dealt with this?