We use 'plastic grass' on our modules for the 16mm modular indoor layout, it does tend to look a bit bright in colour, but has worn well, and gives a more uniform look to any of our modules which have grass on. We have also used it outside on our garden railway in much the same way as Patrick's front boards, as curtains, to cover the items stored under the layout. The top edge we wrapped around a wooden batten (about 5" x 1") which made a low hedge to stop anything escaping in case of a derailment. Not something which happens often. The track is level as we like to run live steam trains, but our garden slopes around 1½ metres from end to end, we thought it would be a wise precaution. The track level is 950mm above our workshop floor (to match modular height), so a little higher above the patio, which is made from the 2" thick slate bed of a snooker table the previous people left in my workshop, a not very forgiving surface if a train should make the leap. By the time the railway gets to the 'top' of the garden the rail level to well below ground level in a return loop tunnel . It does have lift up decking panels over the track in case of accidents, and to remove the 'leaves on the line' during the autumn. We also have some small areas of plastic grass to break up the concrete look of the railway which has a concrete road bed, I spent too much time replacing timber roadbed at our last house/railway in the 25 years we lived there, so I made this one to last, I don't plan to move again, so this one has to last at least as long as I do, which will be another 20 years with any luck.