It's unusual for me to build a carriage without an interior, but, of course the whole point of the Disco Car was that all the furniture was stripped out to make way for the 'dance floor'.
You might think this would be to my advantage - there's less to make - and in that respect you're correct.
However the interiors of our carriages have a structural function as well.
We generally try not to glue our glazing in place but have it floating free, trapped between the inside of the body shell and the outside edges of the seats and tables etc.
I make them to be a neat fit. Sometimes too neat so that when a layer of paint is applied they no longer fit and the sandpaper has to come out!
It also helps to ensure that the bodyside stays straight and does not bend inwards over time.
So what am I going to do on 121 where there is no furniture to hold the glazing in place?
Well, I've come up with this.
They are lengths of L dimension strip glued along the edges of the floor with just enough of a gap - I hope - that they will trap the glazing firmly and help to make the body shell more robust.
I don't believe they will be too obtrusive and in any case I recall that there was a skirt which ran along the edge of each side of the floor in the saloon anyway.