Building a table from scratch is all well and good. However, a plan to work from makes life much easier and we want to keep this on a reasonable budget. This is the coffee table we're using for inspiration for the general look and feel of the table to start with;

The nice thing about this ikea table is that we can replace the open space in the body of the table with our train layout and apply perspex or glass to the outside faces to allow viewing into the layout from more angles. There's plenty of height to work with so we can hide the electronics under the train layout without compromising the floor clearance. We also like the idea of the drawer but we can move that to the under bottom level to give us the storage for the living room "stuff". This is a rough draft of how we'd like it to play out ;

(an artist I am not...)