So, starting with the box.
6 foot long x 18 inches wide. Standard 1x4"
A "lip" of 1x1" stock inside, the top of the 1x1" an inch down from the top of the 1x4"
A 1/4" plywood sheet on top of those "lip" pieces, creating a false bottomed box, that is approx, 3/4" deep, with approx 3 inches of "under" for all the wiring and what have you.
On top of the 1/4" plywood we'll start with 1 inch pink foam insulation and build up from there for elevation(s).
This is the rough drawing of the box concept.
FYI, for those playing along at home...
1. Get a damn life !
2. No, seriously,, my junk isn't that interesting !
3. The concept is based on an article by Richard White, "The ON30 Payless Mine Company" featured in the Sept/Oct 1996 issue of the Narrow Gauge and Short Line Gazette. Hopefully, we'll do it justice, should be able to figure this out,, I've only thought about the article and building a reasonable facsimile for 14+ years !