The story
The term 'Plywood Pacific' mocks North American railroad names like 'Southern Pacific'.
Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: A model railroad layout that lacks scenery, being mostly just trackwork on a bare plywood (or other benchwork top like styrofoam or OSB) Full definition →
The term 'Plywood Pacific' mocks North American railroad names like 'Southern Pacific'.
Etymology from Wiktionary, CC BY-SA 4.0.