This is one of those odd Russian tank designs that just caught my eye and needed to be built.
In 1942 there were several proposals to mount a heavy howitzer on a tank chassis to deal with heavy concrete defensive fortifications. One of the proposals was to mount a 203mm B4 howitzer on the chassis of the KV-1 tank. The project didn't make it past drawing phase and was rejected for obvious reasons.
I designed most of the casemate a gun mount in 3D CAD and had a few of the more complex parts 3D printed. Cleanup wasn't that bad. The supports are pretty small at the contact point and fortunately some of the parts have a cast texture.
I made 2D drawings for the flat parts and cut the sides from sheet styrene stock.
The hull assembly was pretty straight forward. I used Fruil tracks. I think I'm about 1 link too long and will adjust.
Additional info on the U-19 can be found here.