I usually don't build layouts for other people but I took this one on.
The whole is eight feet by 20 inches, and parts in the centre in two sections.
It goes together using the two alignment runners for a coarse alignment, then the two wooden dowel-pins for a final precise match, and finally locked together with a cam-latch rotated by that big hex-key.
Starting in on the track now. The desire is for a test track, hence the separate line next to all the points which will make a reasonably complex "single-scene shunter" design.