There's a thread for this here... https://polycount.com/discussion/56014/how-the-f-do-i-model-this-reply-for-help-with-specific-shapes-post-attempt-before-asking/p163
polygroups > autogroup (or something of that sort) should do that if they're not separate already. Shift+F turns on the wireframe view and also shows your polygroups (separated by colour).
Props practice, dirt booleah modelling, just for desidn full size http://fc09.deviantart.net/fs70/f/2014/328/4/6/control_panel_layout_by_gordeikrasnov-d87keax.jpg