The case I link did not come with inserts.
I have used a great many Hammond cases over the years, probably a few 100.
I have installed 1000s of these brass inserts, in the factory, there is a dedicated installation iron press; as a hobby, I use the method discussed throughout the link thread.
And it only takes seconds to insert these inserts as described.
I do like the black acrylic plastic sheets very much too.
This might be of interest as the panel does not need drilling, just glueing the brass nut assembly as seen in the link below.
This might be of interest too.
