How do I repair a broken polystyrene part?
Forget trying to glue it, repair it some other way. &quot;McGyver&quot; it.
Like maybe buy a lock hasp of appropriate size and use the staple, which is the piece that the lock shackle would go through (see picture). Sorry I could not find a picture of just the staple.
Screw the staple to the speaker body and the staple hole would rest in the base, aligned with the hole in the base. Use a nut and bolt to secure it, with washers and bushings to take up any slack. paint it black to match and only you will know it is there.
Or find some other alternative way to rig it, as glue is likely to disappoint you.