I really like the light/white look of the mounting panel behind the darker wood when looking through the holes on your prototype.
Actually that part IS plastic. ![](http://www.audioroundtable.com/emoticons/smiley.gif)
It's the Delrin shoulder washers used for isolating the connectors and their diameter is virtually the same as the diameter of the through holes that the connectors are protruding through.
I could have just mounted the RCAs without them but the diameter of the shoulder on the shoulder washer was 3/8" and the diameter of the threads on the RCA were some metric dimension so I just made it simple and drilled 3/8" holes. ![](http://www.audioroundtable.com/emoticons/smiley.gif)
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