Steve,

I think construction would depend on is the layout modular or permanent.

My layout is permanent in a finished basement. I have LED lighting on the ceiling but will not put up a valance.

I think more info is needed on what your friend wants to. Cost can be a factor.

What Tom said. An around-the-walls layout with backdrops down the middle of any peninsula is usually a good environment for a valance. How it gets supported depends a lot on the room's ceiling. The simplest ones use lauan plywood or hardboard fastened to a drywall ceiling with brackets and screws. It's enough harder with a suspended ceiling that I can't recall seeing anyone who'd bothered.

Steve,

I posted a couple pixs of my Valance, in another thread. I think there are some considerations to be made, with that. The valance hides the lights, and manages the viewers view, so the distance between the train level and Valance is important.

Construction is important too, mine is done via a shelving system, the same system that my RR is held up on. My intent was to have a easy way to hang the valance on, and control any other room light. The issue I believe he is going to ask is how to hang it from the ceiling...I think I would build a simple frame strong enough to support the lights and the valance. I would hang it off the ceiling joists or hang it via large eyes with chain so he can finish the ceiling.

The other issue is finishing below the railroad edge...I would reflect the Valance.

Valance material, I used bendable Plywood, but then my Valance is nothing but curved surfaces.

I can repost the pictures if wanted. This is an important topic.

Les