Hi again Ian
I have used a few different materials and finishes. Real US platforms tend to be pretty low (some almost level with the track bed).
One of my station platforms (under a shelter) is a sheet of foamboard (the very rigid plastic faced type which is not easy to scribe). I used the hard stuff (free from a local sign maker) because the platform was going to have a building or two placed on it and also figure placement rod-holes drilled into it and I wanted it to be sturdy (the softer stuff, that can be scribed easily, is too light and can dent and also the rod-holes deform).
Another platform came as the base of the building kit itself. I extended it with strips of the same rigid foamboard.
The third station platform was made from the wood bases made by Pola 331793. I cut them to size that I wanted. They are £27 for four and are of a good size.
I hope the photos give a little idea of how they turned out. Apologies for posting so many but I hadn't got any that were directly to do with platforms so I picked a few that showed them from various angles. Some are a bit old.
Beaver Creek station (mainline) the extension was made from the hard foamboard. Some of these pictures are a little old and show only a single through line with one spur , there are now two more passing loops (I grabbed some lawn for these!)
The sandstone blocks are meant as lawn edging but the could also be a platform on t'other side. They had to be moved back as more lawn was 'grabbed' in the following years.
This is the Beaver Creek 'local line station' I bought the shelter with a shattered platform/base and made a new one from hard foamboard. This was scribed with some difficulty using knives and other implements to look like old wood.
The piccy with the RDC-3 does make the track look like it has got a great big 'hump' but it is the effect of using a telephoto lens and 'foreshortening'. There is just a gradual undulation!
Arbour Summit station building sits on the Pola wood bases cut to give the shape needed. The track is actually on a curve and I should have 'carved' the bases to follow the curve but just left it as a straight edge.