Metric stuff & LBSC BAT in Alibre CAD

The first part of this vid is a standard BAT with all the plumbing simplified as far as I can figure it out. (Not having any experience with the real thing)
In the real world I would pump in the cold feedwater further away from the firebox and other stuff
The second bit is the running gear of an O gauge loco that would not fit into a BAT because its all metric.
The wheels are 32mm but there's at least 2mm to spare between the frames for tweaking and fettling and design decisions
I have had a go at making parts for these smaller locos and I really do not
not not like knocking holes under 3mm into the materials I use (weird bug in the text here)
So part of this metric design challenge will be nowt under 3mm, making one of these units is enough of a challenge for most of us ordinary mortals