Playing with the very top of the mountain.
The escaped cars were an accident, but I think I like the concept. :-)
The over/under will both be tunnels, I think.

Need a bit more track.
Some foam risers.
DCC control.
Some trains.
Build some mountains, and structures, etc., etc., etc., ...

Basic construction

Erik built the web frame "sheets".
Need to attach adjustable feet and level things up,
attach to wall, and each other.
Then on to the foam layer.

Racks

Gorilla Racks (and a couple of wall cleats) are used as the structural support for the Monster Modules (sheets).

Sheets and Supports

Semi-modular

Sheets are 3/8 Plywood.
The City Module (above) is 100% reuse. Built on 3/4 or 1/2 ply with feet. No supports needed.
The Logging/Mining "Top Route" is reused, but the old base scrapped.
Sheet dimensions as indicated.

Sheet Support

Supports are 1x4s (or 1x3s?)
Supports are screwed to Sheets.
Sheets and supports sit on racks and wall cleat.
Supports have adjustable feet where they sit on the racks.

Racks and Supports

Figure illustrates position of supports on sheets, and position of feet in relation to racks.

Latest incarnation,...