A nice thin 1/4 inch ply core followed by that cheap silver bubble wrap (for spacing) followed by the plastic sheeting I have would work pretty good...
I plan on riveting the plastic into the steel frame, and now that you mention it, I could rip some battens to attach to the ply, which would provide a thick enough material to add a few rivets in the middle of the panel too.
My plan for the outside edges is this plastic u channel stuff that has a 1-1/8" inner width. I can clip it right over the edges where metal is at.
For the edges at the ceiling curve I was planning on some thin cove base molding (100 foot reels of the stuff is cheap) installed upside down and fastened to the panel. It would make a great wire chase for things too.
Originally Posted by Vlad
I decided to use 1/4" plywood. I will use 3/4" or 1" or 1.5" wood framing and fill voids with foam I have. I will use Bondo compound where I have gaps.
I might use some steel where really needed, but bus itself is rock solid and partition walls made of steel are overkill....
So in my case it will be more like house drywall. Drywall is 1/4" plywood, mud is Bondo. It is very forgiving if you screw up (and believe me you will...) you can easily fix just about anything with Bondo.....
If I were you I would use 1/4" plywood. I would add some wood between steel studs you have. I would use screws/glue to screw ply to metal and brad nails/glue to attach ply to wood. I would add horizontal wood runs every 12-18". This would give enough support for whatever material you decide to use.
I had to add wood in some areas because plywood needs support especially where 2 ply sheets meet.
The real PITA for you are inside corners. You can double up steel with 1"x2" and attach ply to it.
Think ahead. How are you going to make your inside/ outside corners? What is going to be used as a filler compound? If you don't want to use filler you will have to use some kind of mouldings everywhere.