Made by Moby.
Two sets of aligning steel tubes, very popular as coaster supports. They are quarter-tile based and can be used to make unique support structures of many different shapes and sizes.
Objects will not move up or down when editing terrain. This means you can build a coaster on flat terrain, build all the supports (which is easier on flat terrain), then terraform as you wish without messing up the height of the supports.
Extract the file and place the two folders into style\themed as usual.