here is a inside picture
my construction is made with 5mm copper plate and Pomona 3770 posts directly screwed in, because I did not want any other metal involved
(not even the screw nuts provided with the pomona binding posts)
my main focus was "perfect" symmetry
(and it came out very well: mechan. it is within about 0.01mm in any dimension and el. so far it shows less than 1µOhm change in any plug combination I tried)
only the screw thread gave me trouble, because the binding posts have more than expected tolerances
because of that, the screws are very close fitting (and one of my 3770 broke off), but becuase of very fast oxidation I like the fact that the screws are most probably gas tight and therefore hopefully no need to have it gold plated