A fluid conduit system (1900; 2000), comprising: at least one panel (310; 1910A; 12010,2210) having a constant cross-section; a first plurality of conduits (308; 1908A; 2008), each extending through a respective one of said at least one panel; a first manifold (1950; 2050) in fluid connection with said first plurality of conduits; and a second manifold in fluid connection with said first plurality of conduits, wherein each of said at least one panel comprises: a first major face; and a second major face opposite said first major face, characterized in that: a peripheral outline of said panel has substantially a shape of a rectangular cuboid excepting a first recessed portion along a first edge of said first major face and a second recessed portion along a second edge of said second major face diagonally opposite said first edge, and said first and second recessed portions define counterparts (322, 333) of an engagement mechanism that inhibits lateral motion of said panel away from another said panel when said first recessed portion is in counterpart engagement with said second recessed portion of said another panel. at least one panel (310; 1910A; 12010,2210) having a constant cross-section; a first plurality of conduits (308; 1908A; 2008), each extending through a respective one of said at least one panel; a first manifold (1950; 2050) in fluid connection with said first plurality of conduits; and a second manifold in fluid connection with said first plurality of conduits, wherein each of said at least one panel comprises: a first major face; and a second major face opposite said first major face, characterized in that: a peripheral outline of said panel has substantially a shape of a rectangular cuboid excepting a first recessed portion along a first edge of said first major face and a second recessed portion along a second edge of said second major face diagonally opposite said first edge, and said first and second recessed portions define counterparts (322, 333) of an engagement mechanism that inhibits lateral motion of said panel away from another said panel when said first recessed portion is in counterpart engagement with said second recessed portion of said another panel. a first major face; and a second major face opposite said first major face, characterized in that: a peripheral outline of said panel has substantially a shape of a rectangular cuboid excepting a first recessed portion along a first edge of said first major face and a second recessed portion along a second edge of said second major face diagonally opposite said first edge, and said first and second recessed portions define counterparts (322, 333) of an engagement mechanism that inhibits lateral motion of said panel away from another said panel when said first recessed portion is in counterpart engagement with said second recessed portion of said another panel. a peripheral outline of said panel has substantially a shape of a rectangular cuboid excepting a first recessed portion along a first edge of said first major face and a second recessed portion along a second edge of said second major face diagonally opposite said first edge, and said first and second recessed portions define counterparts (322, 333) of an engagement mechanism that inhibits lateral motion of said panel away from another said panel when said first recessed portion is in counterpart engagement with said second recessed portion of said another panel.