There's lots of options available for creating backdrops for model railroad backdrops. Masonite, roll aluminum, floor lino, to name a few.
I've used Masonite in the past, but this time I've decided to try sheet styrene. Masonite requires a lot of fasteners, thus much puttying to fill all those holes up, as well as it's not very stable with temperature and humidity shifts. Every joint on the old layout cracked in spite of the taping of the joints. I'm hoping/expecting that the styrene will be more resistant to seasonal changes.
Much credit for this decision must go to my friend Trevor Marshall. Basically he talked me into it. Trevor and I bounce ideas off of each other on a regular basis and it was he who said why not use 0.060" styrene. After considering the idea for about 2 minutes, I said "why not indeed?".
So first I bought 3 sheets of styrene and cut it into 16" wide strips.
I then sawed up some 3/4" square stock and made some rudimentary frames which will support the plastic. These were secured to the rear of the benchwork. You can see that I didn't bother creating support for the actual corners. I believe that the material will do an adequate job supporting itself.
Time will tell.
I simply cut off a couple of 2" wide strips, shorten them enough to fit between the framing members and glued to the first sheet with solvent cement.
The seams are being filled with spot putty.
You'll note that I've kept the backdrop down from the ceiling. It tops out at 64 inches, which is just below eye level for me. I've done this for a couple of reasons.
The basement gets lots of daylight and I don't want to lose that. I also don't want to restrict airflow with a 35' long additional barrier.
And lastly, the backdrop is there to control the view of the layout and the chosen height will do that nicely with the benchwork height I've chosen.
The actual painting of the backdrop will be rather "neutral". I do not subscribe to the current fashion of photo mural backdrops. Backdrops should not upstage the layout, but rather assist in focusing attention onto the primary subject, the trains and the immediate surrounding scenery.
I would have followed Trevor's lead and hung a neutral grey cyclorama all the way around, but this room and this layout doesn't lend itself to that approach.
Once I get some blue paint flung, I can return to the driveway and mill more Homasote. Who has more fun than us?