Some time ago I've picked up a H0 scale railing set from Auhagen (Auhagen 42558). I bought it mostly for the bridge railings I use as ladders on my sci-fi terrain pieces (see here), but I thought that I will eventually find some use for the other two types included in the pack. I guess I was right:
Those are probably the most simple terrain pieces I've ever made - it took me less than half an hour to make the above pieces - and most of that time was spent on painting.
It gets down to the following:
1. Cut two strips of fieldstone-textured decorflex, 20cm long and 1cm wide.
2. Glue them back-to-back with a bit of PVA glue.
3. When the glue is still drying, push the plastic fencing between the two strips of Decorflex. As the fencing is slightly longer than 20cm, you may want to cut the last bar with some modelling clippers.
4. Cut a strip of 1mm plasticard or PVC, 20cm long and 1-1,2 cm wide and glue the wall to it. This will make your fences more stable and sturdy.
5. Paint to match the rest of your terrain.
I've also started to work on a bigger piece: a ruined Mordheim tower with an overstreet bridge - the pictures below show the very first stages of building the tower, but I guess they give an overall idea of where I'm going with it: