DB wagon with sliding roof 1:87 (H0)

Wagen mit Schiebedach der Bauart Kmmks, Gattungsbezirk Dusseldorf.

German wagon with sliding roof - early prototype of Kmmks 51.
This drawings was used: http://scaletrainsclub.com/board/download/file.php?style=7&id=53580&mode=view.

Model on photos is using shortened chassis of https://www.thingiverse.com/thing:3308250.