The ArsenalM HO scale 17 cm WWII German howitzer is a very complicated model. I have been making slow progress as I work on it off and on. It builds up to a very nice model, but the instructions are pretty poor. They are a series of line drawings and are very small. They don't show both sides of the model.
The etched brass parts add a lot of very fine detail. The barrel is turned aluminum. I found the barrel did not fit exactly correct and so I added a tiny bit of sheet styrene to hold it up a bit. You can see the white part in some of the photos.