When Llynfordd was fist started I had the idea to scratch-build a couple of relay boxes - then Wills popped up with two packs of ready to run examples. Now I'm all for scratch-building for the sake of individuality and to save a couple of quid, but I couldn't get near this level of detail and it would have taken me hours.
The two above cost the price of a pint and it took longer for the chap at the Hobby Box to find them in the back room than it did for me to put them together.
An article that appeared when they came out suggested mounting on a 40 thou base to represent a concrete apron. The photo below at Crawley shows the boxes on the ground and surrounded by a mess of concrete trunking. The guard rails are an interesting addition though.