Hey, me again! Did you know there's a slight problem with your main_crystal2 part? I've just printed it and thought there was something wrong with my printer (I've been having belt tensioning issues). Take a look at the model, viewed from the top. The distance between the 2 outer parts get smaller the further around the model you go.
Probably not a big deal as it'll be covered by the upper_center but just thought I'd let you know.