HWT wood chip container I

Part of my layout will feature a sawmill scene, with the sawmill itself "out of scene" and only part of a storage building / loading shelter and woodchip silo visible. For the woodchip silo I'll of course need woodchip wagons... and the HWT wood chip containers seem to be the perfect fit for a 1990s layout:
From NZR Rolling Stock Lists
The majority of the wood chip containers are HFC class. These are just converted ISO containers, with the roofs taken off. The HWT class were meant as a better alternative to containers, they had greater capacity and, more importantly, could tip when a hydraulic ram was applied to unload the woodchips.

From KiwiBonds
HWT 16, pictured above, was the prototype which came out in 1993. It was originally painted grey, as per the KiwiBonds pic above, but was later re-painted green with a Railfreight logo applied, and the branding "FibreLiner" (which was the style at the time... along with "SpaceRunner" for the ZH class, "SpaceRacer" for the ZG class and I'm sure plenty of other brand names). Named wagons was some sort of 90s thing.

HWT 16 was an orphan for three years until the then Tranz Rail, as NZ Rail became in 1995, had won the woodchip traffic from Portland - Port Whangarei. The production HWTs were significantly taller and shorter than the prototype, but were also 'tipping' and operated by hydraulic rams.

In my fantasy world, the original prototype went into production, hence I can have multiple HWTs mounted on UK wagons with woodchip traffic.

I'm also in the process of designing on the hoof a woodchip silo (see my other thoughts here), more on that later. Before I do I need some basic measurements for the container to get the silo's height correct. So I rapid-prototyped a container this evening in front of TV, thanks to the plans being available in the February 2005 edition of the NZ Model Railway Journal:

The plans were photocopied and glued to cardboard.
 It was one of those basic squares with a few flaps added jobs, but it did the trick:
HWT at the site of the yet-to-be-built woodchip silo.
As you can see, the sides are bent inwards, to fit within the loading gauge.
 Eventually I'll get around to making one (probably with the outer parts 3D printed)...