Where I work now we produce some custom items in house so all sorts of interesting shipping material arrives . . . and so does 3 foot reinforced cardboard tubes used for rolls of steel mesh. Its all getting thrown away unless I grab it so . . . I now have a 3 foot roll that is 4 inches or so in diameter, which makes it 4 levels wide IIRC.
This of course screams pipeline segment . . . which means that once I get it based & painted it will be a terrain piece that will stretch from one side of the hotmatz to the next on the narrow portion.
But what else to put with it?
I am thinking of building a pumphouse/monitoring station (3x4 hexes?) which would go up and on top of the pump, look industrial and 'control' the flow. I would set up a 'mech path' across the pipeline with elevators on each side to allow maintenance equipment to move from one side to the other. I also think a airlock or something like that to allow access into the pipeline when its not operational for inspection. I also want a smaller pipe option where I can connect another smaller pipe (1 level, maybe 2 tall) so I could use the pumphouse as a t-junction. I think one edge of the pumphouse should also be flat where I could take a second section later to put it against the pumphouse to make a full sized t-junction of the two tubes of the same size.